Fuel cell coupled flow battery energy supply system and operation control method thereof

Abstract

The invention discloses a fuel cell coupled flow battery energy supply system and an operation control method thereof. The energy supply system comprises a basic energy supply unit, an energy storage peak regulation unit, a renewable energy power generation unit, an electrolytic hydrogen production unit, a hydrogen storage unit, a first-stage waste heat recycling unit, a second-stage waste heat recycling unit and a heat storage unit. The basic energy supply unit is used for providing a basic power load of the target building group; the energy storage peak regulation unit is used for providing fluctuation power load of the target building group; the first-stage waste heat recycling unit receives first-stage waste heat generated by power generation of the fuel cell and is used for indoor heating or indoor refrigeration. And the second-stage waste heat recycling unit directly receives the first-stage waste heat or second-stage waste heat from the first-stage waste heat recycling unit and is used for preheating the electrolyzed water and / or the hydrogen storage unit. By arranging the first-stage waste heat recycling unit and the second-stage waste heat recycling unit, waste heat is utilized in a multi-stage mode according to requirements, and the waste heat utilization rate is high.

Description

Technical Field

[0001] The present application relates to the field of integrated energy supply technology, and in particular to a fuel cell coupled flow battery energy supply system and an operation control method thereof. Background Art

[0002] Due to the randomness and intermittent nature of renewable energy, energy storage is crucial for maintaining a balanced power system and supporting energy transition. Taking battery energy storage systems as an example, many provinces have mandated the installation of energy storage at renewable energy sites. Despite this, due to geographical and climatic constraints, energy storage systems have low utilization rates and face challenges such as insufficient renewable energy absorption capacity, a lack of cross-seasonal energy scheduling, and limited peak-shaving flexibility.

[0003] To address these issues, energy supply systems that can meet peak load requirements have emerged on the market. However, these systems generate waste heat during operation, but their utilization is low and requires further improvement. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides an energy supply system of a fuel cell coupled with a liquid flow battery and an operation control method thereof.

[0005] The fuel cell coupled flow battery energy supply system includes: A basic energy supply unit that uses fuel cells to generate electricity to meet the basic power load of the target building complex; Energy storage peak shaving units, which use flow battery energy storage to meet the fluctuating power loads of the target building complex; a renewable energy power generation unit that utilizes renewable energy to generate electricity for water electrolysis or storage in the flow battery; an electrolysis hydrogen production unit that utilizes electricity generated by a renewable energy power generation unit to electrolyze water to produce hydrogen; A hydrogen storage unit, which is used to store hydrogen and release hydrogen in a timely manner for the fuel cell to generate electricity; a primary waste heat recovery unit, which receives the primary waste heat generated by the fuel cell for indoor heating or indoor cooling of the target building complex; A secondary waste heat recovery unit, which directly receives the primary waste heat generated by the fuel cell power generation or the secondary waste heat from the primary waste heat recovery unit, and is used for preheating the water electrolysis and / or hydrogen storage unit; The heat storage unit is used to store the primary waste heat generated by the fuel cell power generation or the secondary waste heat from the primary waste heat recovery and utilization unit.

[0006] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution. They are merely further supplements or optimizations. Under the premise that there are no technical or logical contradictions, each optional method can be combined separately for the above-mentioned overall solution, or multiple optional methods can be combined.

[0007] Optionally, the flow battery is preheated using waste heat stored in the heat storage unit.

[0008] Optionally, the renewable energy power generation unit includes a wind power generation unit and a solar power generation unit.

[0009] Optionally, a hydrogen combustion heating unit is included for indoor heating of the target building complex.

[0010] Optionally, a backup power generation unit is included to generate electricity to meet the basic power load of the target building complex when the basic power supply unit is shut down.

[0011] Optionally, an oxygen storage unit is included, which is used to store oxygen and release oxygen to supply the fuel cell and / or liquid flow battery to participate in the oxidation reaction.

[0012] The present application also provides an operation control method for a fuel cell coupled flow battery, comprising: Fuel cell power generation meets the basic power load of the target building complex, and flow batteries supplement the power load gap during peak hours; The waste heat generated by fuel cell power generation is used for one or more of indoor cooling, indoor heating, preheating electrolyzed water, preheating hydrogen storage units, and storing in heat storage units according to seasonal conditions; The electricity generated by the renewable energy power generation unit is first stored in the energy storage peak-shaving unit, and the excess electricity is used to electrolyze water to produce hydrogen.

[0013] Optionally, in summer, the primary waste heat generated by fuel cell power generation first meets the indoor cooling needs of the target building complex, and the secondary waste heat is stored in the heat storage unit; In winter, the primary waste heat generated by fuel cell power generation is first used to meet the indoor heating needs of the target building complex, and the secondary waste heat is used to preheat the electrolyzed water and / or hydrogen storage unit; In spring and autumn, the primary waste heat generated by fuel cell power generation is directly used to preheat the electrolyzed water and / or hydrogen storage unit, and the remaining part is stored in the heat storage unit.

[0014] Optionally, when the actual power of the flow battery is less than 30% of the rated power, it is charged, and when the actual power of the flow battery is greater than 80% of the rated power, charging is stopped.

[0015] Optionally, an oxygen storage unit is included, which is used to store oxygen and release oxygen to participate in the oxidation reaction with the fuel cell and / or liquid flow battery. The oxygen distribution valve opening is obtained according to the following prediction function: , , when the M value is the minimum, the corresponding That is the optimal solution for oxygen distribution; Prediction function for optimal oxygen delivery:

[0016] in, , is the oxygen utilization rate, is the oxygen concentration in the cathode cavity of the flow battery (mol / m³), is the oxygen utilization rate of the fuel cell cathode (%); is the relative saturation concentration of oxygen in the flow battery; is the energy cost of oxygen production, is the power of the oxygen production system, is the electricity price at that time; To quantify the life loss cost of oxygen compressors, is the compressor speed, is the relative speed; α, β, and γ are weight coefficients, α=0.5, β=0.3, and γ=0.2.

[0017] The present application discloses a fuel cell coupled liquid flow battery energy supply system and an operation control method thereof. By providing a primary waste heat recovery and utilization unit and a secondary waste heat recovery and utilization unit, waste heat is utilized in multiple stages according to demand, and the waste heat utilization rate is high. At the same time, a large amount of waste electricity generated by the renewable energy power generation unit can be used to electrolyze water to produce hydrogen and oxygen. The produced hydrogen is used as fuel for power generation by a fuel cell with high power generation efficiency. At the same time, the produced oxygen is used in the chemical reaction processes of liquid flow battery power storage and fuel cell power generation respectively through an optimized oxygen supply mode. The energy system is then powered by a "day-season" dual time scale coordinated energy control strategy, thereby maximizing the comprehensive energy efficiency of the liquid flow battery and fuel cell coupled energy supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the total daytime power supply load of a target building complex according to an embodiment of the present application; Figure 2 This is a schematic diagram of the structure of the fuel cell coupled flow battery energy supply system in summer and winter according to an embodiment of the present application; Figure 3This is a schematic diagram of the structure of the energy supply system of a fuel cell coupled with a flow battery in spring and autumn according to an embodiment of the present application; Figure 4 This is an oxygen execution scheduling logic diagram of an embodiment provided by this application; Figure 5 This is a flowchart of oxygen allocation decision-making in MPC optimization in an embodiment provided by this application; Figure 6 This is a schematic diagram of the structure of each unit of the energy supply system of the fuel cell coupled liquid flow battery controlled by the central control system.

[0019] The reference numerals in the figures are described as follows: 100. Basic energy supply unit; 200. Energy storage peak shaving unit; 300. Renewable energy power generation unit; 310. Wind power generation unit; 320. Solar power generation unit; 400. Electrolysis hydrogen production unit; 500, hydrogen storage unit; 510, oxygen storage unit; 600, primary waste heat recovery and utilization unit; 610, secondary waste heat recovery and utilization unit; 700, heat storage unit; 800. Hydrogen combustion heating unit; 900, standby power generation unit; 910, standby gas supply unit. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0021] It should be noted that when a component is referred to as being "connected" to another component, it may be directly connected to the other component or there may be an intermediate component. When a component is referred to as being "disposed on" another component, it may be directly disposed on the other component or there may be an intermediate component.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] In this application, the terms "first," "second," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number or order of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0024] In this application, the terms "comprises" and "comprising" and any variations thereof are intended to cover non-exclusive inclusions, for example, a system, product or apparatus comprising a list of elements is not necessarily limited to those elements expressly listed but may include other elements not expressly listed or inherent to such products or apparatuses.

[0025] See also Figures 1 to 3 An embodiment of the present application provides an energy supply system for a fuel cell coupled with a liquid flow battery, including a basic energy supply unit 100, an energy storage and peak-shaving unit 200, a renewable energy power generation unit 300, an electrolysis hydrogen production unit 400, a hydrogen storage unit 500, a primary waste heat recovery and utilization unit 600, a secondary waste heat recovery and utilization unit 610, and a heat storage unit 700.

[0026] The basic energy supply unit 100 utilizes fuel cells to generate electricity to meet the basic power load of the target building complex. In this embodiment, the fuel cell is a high-temperature solid oxide fuel cell (SOFC). Once the SOFC reaches operating temperature (700-1000°C), it can generate electricity continuously 24 hours a day, providing a stable power supply to the target building complex. In this application, the target building complex can be a building park, such as an industrial park or a commercial park.

[0027] Since the liquid flow battery has the performance of rapid response to charge and discharge, the energy storage peak shaving unit 200 utilizes the liquid flow battery energy storage to meet the fluctuating power load of the target building complex.

[0028] like Figure 1 The figure shows the total daytime power supply load of the target building complex, where the building fluctuating power load = the total building power load - the building basic power load, the SOFC is used to provide the building benchmark power load, and the flow battery is used to provide the building fluctuating power load.

[0029] The renewable energy generation unit 300 generates electricity from renewable energy, which is then used for water electrolysis or stored in a flow battery. In this embodiment, the renewable energy generation unit 300 includes a wind power generation unit 310 and a solar power generation unit 320. The wind power generation unit 310 utilizes a wind turbine, while the solar power generation unit 320 utilizes photovoltaic power. Of course, given the randomness and intermittent nature of power generation from the renewable energy generation unit 300, to ensure sufficient storage capacity in the flow battery, the flow battery stores electricity partially from the renewable energy generation unit 300, with the remainder coming from commercial power (primarily nighttime off-peak electricity). Building on the stable power supply provided by the SOFC, the flow battery stores nighttime off-peak electricity, releasing it during daytime peak hours to reduce the proportion of high-priced grid electricity purchased by the target building complex.

[0030] The electrolysis hydrogen production unit 400 uses the electricity generated by the renewable energy power generation unit 300 to electrolyze water to produce hydrogen (and simultaneously produce oxygen). Of course, when the electricity generated by the renewable resource power generation unit is insufficient, commercial off-peak electricity can also be used to electrolyze water to produce hydrogen.

[0031] The hydrogen storage unit 500 is used to store hydrogen and release it in a timely manner to generate electricity for the fuel cell. In this embodiment, the hydrogen storage unit 500 uses a magnesium-based solid-state hydrogen storage device, which stores and releases hydrogen through a reversible reaction between hydrogen and metallic magnesium. The reaction formula is as follows: Mg+H2→MgH2 (hydrogen storage mode) MgH2→Mg+H2 (hydrogen release mode) The operating temperature of SOFC during power generation is 700℃-1000℃, and high-temperature waste heat will be generated during power generation. In order to fully utilize this high-temperature waste heat, the first-level waste heat recovery and utilization unit 600 of this application receives the first-level waste heat generated by fuel cell power generation and is used for indoor heating or indoor cooling of the target building complex.

[0032] Considering the full utilization of waste heat, the secondary waste heat recovery unit 610 directly receives the primary waste heat generated by the fuel cell power generation or the secondary waste heat from the primary waste heat recovery unit 600 for preheating the electrolyzed water and / or the hydrogen storage unit 500.

[0033] In one embodiment, the temperature of the first-stage waste heat is 600°C, and the temperature of the second-stage waste heat is 300°C.

[0034] The hydrogen storage unit 500 typically stores hydrogen within a temperature range of 300°C to 400°C. This high temperature environment can be achieved by utilizing the secondary waste heat (around 300°C) generated by SOFC power generation. Furthermore, the hydrogen storage reaction typically requires a relatively high hydrogen pressure of 2MPa to 4MPa. Under these specific temperature and pressure conditions, magnesium and hydrogen combine to form magnesium hydride.

[0035] When releasing hydrogen, the reaction usually needs to be carried out in a high-temperature environment above 300°C. Therefore, the hydrogen release reaction also provides a direction for utilizing the waste heat generated by SOFC power generation, that is, magnesium hydride decomposes when heated (300°C) to release hydrogen again.

[0036] The heat storage unit 700 is used to store the primary waste heat generated by the fuel cell power generation or the secondary waste heat from the primary waste heat recovery unit 600.

[0037] In one embodiment, an oxygen storage unit 510 is included, which is used to store oxygen and release the oxygen to supply the fuel cell and / or the flow battery to participate in the oxidation reaction.

[0038] In one embodiment, the flow battery is preheated using waste heat stored in the heat storage unit 700 .

[0039] In one embodiment, the heat storage unit 700 may utilize a phase change heat storage material (paraffin wax, melting point 50° C.) to store heat.

[0040] In one embodiment, to address the issue of insufficient indoor heating, the energy supply system also includes a hydrogen combustion heating unit 800 for indoor heating of the target building complex. In this embodiment, hydrogen released from the hydrogen storage unit 500 enters the hydrogen combustion heating unit 800 to generate hot water / steam, which further provides indoor heating (though it can also be used for other purposes, such as steam sterilization). In this embodiment, the hydrogen combustion heating unit 800 can be a hydrogen boiler.

[0041] In order to ensure that the SOFC and / or hydrogen combustion heating unit 800 has sufficient fuel, the energy supply system also includes a backup gas supply unit 910, which can provide natural gas when hydrogen is insufficient to enable the SOFC and / or hydrogen combustion heating unit 800 to operate normally.

[0042] In one embodiment, to cope with emergencies, the energy supply system includes a backup power generation unit 900. This unit generates electricity to meet the base power load of the target building complex when the base power supply unit 100 shuts down (stops operating or malfunctions). In the figure, the backup power generation unit 900 specifically refers to a gas turbine.

[0043] See also Figure 2~Figure 3, an embodiment of the present application further provides an operation control method for an energy supply system of a fuel cell coupled with a liquid flow battery, comprising: the fuel cell generates electricity to meet the basic power load of the target building group, and the liquid flow battery supplements the power load that is not met during the peak period; The waste heat generated by fuel cell power generation is used for one or more of indoor cooling, indoor heating, preheating electrolyzed water, preheating hydrogen storage unit 500, and storing in heat storage unit 700 according to seasonal conditions; The electricity generated by the renewable energy power generation unit 300 is first stored in the energy storage peak regulation unit 200, and the excess electricity is used to electrolyze water to produce hydrogen.

[0044] The waste heat utilization of fuel cells in different seasons is as follows: Example 1: Summer time See also Figure 2 In hot weather, indoor cooling is required. The primary waste heat generated by fuel cell power generation first meets the indoor cooling of the target building complex, and the secondary waste heat is stored in the heat storage unit 700.

[0045] Specifically, the SOFC's high-temperature waste heat (600°C) flows through the primary waste heat recovery unit 600 and enters a lithium bromide absorption chiller, where it is used to produce chilled water. This chilled water is then used to cool the target building complex. After cooling the indoor space, the secondary waste heat recovery unit 610 receives the secondary waste heat (300°C) from the primary waste heat recovery unit 600 and stores it in the thermal storage unit 700. When the flow battery's electrolyte solution temperature drops, affecting storage and discharge performance, the waste heat stored in the thermal storage unit 700 is released to increase the flow battery's electrolyte solution temperature, thereby improving storage and discharge efficiency. In this embodiment, this efficiency can be increased by 15%.

[0046] Example 2: Winter See also Figure 2 , the outside temperature is low, and the primary waste heat (600℃) generated by fuel cell power generation first meets the indoor heating (hot water and high-temperature steam) of the target building complex. For example, medical buildings require a large amount of steam and hot water for disinfection and cleaning. The secondary waste heat is used to preheat electrolyzed water and / or hydrogen storage unit 500.

[0047] Specifically, the SOFC's high-temperature waste heat (600°C) is first transferred to the primary waste heat recovery unit 600 for winter heating of the target building complex. The secondary waste heat recovery unit 610 receives the secondary waste heat (300°C) from the primary waste heat recovery unit 600 to preheat the electrolyzed water in the hydrogen production unit 400 and / or the hydrogen storage unit 500. The preheated electrolyzed water is then electrolyzed into hydrogen and oxygen. The oxygen is transported and stored in the oxygen storage unit 510, while the hydrogen enters the hydrogen storage unit 500. In this embodiment, during winter, the secondary waste heat is used to preheat both the electrolyzed water and the hydrogen storage unit 500. This not only improves the efficiency of hydrogen production from the electrolyzed water, but also provides the heat required for hydrogen storage / release in the hydrogen storage unit 500, thereby increasing the efficiency of hydrogen storage / release. Of course, if heating is insufficient, a hydrogen boiler can be used to burn hydrogen for further indoor heating.

[0048] Example 3: Spring and Autumn See also Figure 3 The target building complex does not have a large demand for cooling and heating loads, so the primary waste heat generated by fuel cell power generation is directly used to preheat electrolyzed water and / or hydrogen storage unit 500, and the remaining part is stored in the heat storage unit 700.

[0049] Specifically, the waste heat generated by the operation of the SOFC is mainly used to preheat the electrolyzed water and the electrolyte of the liquid flow battery to improve efficiency. Another part of the waste heat is stored in the heat storage unit 700. That is, when the temperature of the electrolyte solution of the liquid flow battery drops, the heat storage unit 700 releases the waste heat to increase the temperature. Of course, these two parts of waste heat can be interconnected and allocated.

[0050] Generally, the power generation efficiency of current commercial SOFCs is generally between 50% and 65%, and the highest theoretical power generation efficiency of SOFC can reach 70% to 85%. In order to improve the waste heat utilization rate of SOFC, this application adjusts the use of waste heat according to different seasons and effectively utilizes the waste heat in a tiered manner, so that its comprehensive energy efficiency can reach more than 90%.

[0051] In one embodiment, the power generation of wind power generation unit 310 and solar power generation unit 320 varies seasonally due to atmospheric circulation and topography. Most regions experience abundant wind resources in spring and winter, while wind speeds decrease in summer and autumn. For example, in northwest China, average winter wind speeds can reach over 1.5 times those in summer, resulting in significant differences in power generation. Solar radiation intensity varies with latitude and season. In northern China, the average daily effective sunlight duration in winter is 30%-50% shorter than in summer, and snow cover further reduces power generation efficiency.

[0052] When solar energy resources are abundant in the summer, the energy supply system of the present application will convert solar energy into electrical energy in the form of photovoltaic power generation, and then store hydrogen in the summer through electrolysis. At the same time, commercial valley electricity in the low-valley price range at night can be used to effectively supplement additional electrolysis hydrogen production, and the peak-valley electricity price difference can be used to store hydrogen during valley hours and use hydrogen during peak hours to increase the economic efficiency of the overall energy system operation. Of course, the oxygen produced by electrolysis hydrogen production can be stored in the oxygen storage unit 510 (such as an oxygen tank) for commercial use, thereby ensuring the overall economic operation of the energy supply system. In addition, the present application also uses part of the oxygen for liquid flow batteries and fuel cells to enhance the energy efficiency of the energy supply system.

[0053] The liquid flow battery in this application, such as the all-vanadium liquid flow battery, relies on the change of ion valence in the electrolyte. , the charge and discharge reactions of the positive and negative electrodes consume active substances in the electrolyte. By introducing oxygen into the positive electrode electrolyte of the liquid flow battery as an external oxidant to participate in the reaction, the consumption of high-valent ions in the electrolyte can be reduced, thereby increasing the energy storage capacity of the electrolyte per unit volume by 20-30%, reducing the burden of high-valent ion reduction, and slowing down the attenuation of active substances. Oxygen enters the positive electrode of the liquid flow battery as an oxidant and reacts with the positive electrode electrolyte. The following oxidation reaction occurs: This measure reduces the amount of charging energy required to oxidize the positive electrolyte, directly utilizing readily available oxygen. This reduces the flow battery's charging energy consumption by 18%, further effectively improving the overall energy efficiency of the energy supply system. Furthermore, some of the produced high-purity oxygen is used as an oxide in the hydrogen generation reaction within the SOFC fuel cell, further enhancing the SOFC fuel cell's power generation efficiency.

[0054] To optimize oxygen supply, see Figure 4 , is the execution scheduling logic diagram of oxygen. Specifically, the dynamic allocation of oxygen is as follows: In one embodiment, when the renewable energy generation unit 300 generates sufficient electricity, it utilizes excess wind and solar power to maximize water electrolysis for oxygen production (hydrogen production also generates oxygen). Oxygen is preferentially injected into the flow battery, reducing the flow battery's charging power consumption. Because excess wind and solar power is also present, a large portion of the wind and solar power is also fed into the flow battery.

[0055] One embodiment: When the building load suddenly increases during the evening peak, the flow battery discharges and the remaining oxygen is supplied to the SOFC fuel cell.

[0056] One embodiment: When wind and solar power generation drops suddenly, the flow battery is switched to a discharge state, and oxygen is preferentially supplied to the SOFC fuel cell to generate electricity to supply the power load required by the building.

[0057] In summary, after renewable energy generation unit 300 generates electricity, it enters the flow battery for storage. The flow battery then discharges electricity to supply the fluctuating power load of the target building complex. When renewable energy generation unit 300 is generating sufficient electricity (as in the summer when solar radiation is strong), the electricity generated by solar power generation unit 320 is not only stored in the flow battery, but the remaining electricity is also used for the electrolysis hydrogen production unit (hydrogen production and the generated oxygen is stored in the oxygen tank). Because the flow battery is in high-capacity charging mode when the renewable energy generation unit is generating sufficient electricity, and charging mode requires a large amount of oxygen, the oxygen stored in the oxygen tank is preferentially supplied to the positive electrode of the flow battery to improve charging efficiency.

[0058] When renewable energy generation unit 300 is generating insufficient energy (e.g., in winter when solar radiation is weak), the generated electricity is preferentially stored in the flow battery. During the majority of the day, the flow battery is in discharge mode, supplying power to the target buildings. During discharge mode, the flow battery has a low oxygen demand, so oxygen previously stored in the oxygen tank is preferentially supplied to the fuel cell. Because when renewable energy generation unit 300 is generating insufficient energy, the fuel cell must increase its load factor to generate more electricity for the target buildings. This means that fuel cell power generation requires a higher level of pure oxygen. Therefore, when wind and solar power generation is insufficient and the fuel cell needs to generate more electricity, oxygen is preferentially supplied to the SOFC.

[0059] In one embodiment, a predictive control (MPC) model for optimizing oxygen delivery is provided, as follows: Core architecture of the MPC optimization model 1. State-space equations State variables: : oxygen tank pressure (MPa); : oxygen concentration in the cathode cavity of the flow battery (mol / m³); : Fuel cell cathode oxygen utilization rate (%); Control variables: : oxygen production system power (MW); : compressor speed (rpm); : Oxygen distribution valve opening, ,like , it means that 80% of oxygen is supplied to the flow battery and 20% to the fuel cell; if , it means that 80% of the oxygen is supplied to the fuel cell and 20% of the oxygen is supplied to the flow battery; if , it means that all oxygen is supplied to the fuel cell.

[0060] 2. Objective Function

[0061] in, is the oxygen utilization rate, that is, the percentage of oxygen actually participating in the reaction in the total supply. Its value tends to be 95% which is the ideal state. When the fuel cell Close to the theoretical maximum efficiency of 98%, the relative oxygen concentration saturation of the flow battery About 88% is the safety threshold to ensure reaction efficiency. (Comprehensive oxygen utilization index, is the fuel cell oxygen utilization rate, is the relative saturation concentration of oxygen in the flow battery, is the absolute concentration (mol / m 3 ), must pass Normalized to relative saturation. Oxygen is dominant in fuel cells, so the coefficient is set in this application The coefficient is 0.7), based on the maximum efficiency of 98% and the optimal oxygen relative concentration saturation of 88% of the above fuel cells and flow batteries, The oxygen utilization rate tends to be 95% which is the best; is the energy consumption cost of oxygen production, the smaller the value, the better. is the electricity price at that time; To quantify the life loss cost of oxygen compressors (yuan / hour), this is a simplified calculation formula for actual engineering (measured consistency >90%). The lower the life loss cost, the better. is the compressor speed, and the comprehensive life wear of the compressor is the aerodynamic loss ( )、Fatigue loss( ) and friction loss ( ), where is the corresponding coefficient. According to engineering measurements, aerodynamic loss accounts for 65% of the total loss, and fatigue damage can be approximated as , the friction loss can be completely ignored, and the relative speed is defined as , then the comprehensive life wear cost of the compressor is approximately ,Right now .

[0062] Therefore, the objective function of the superposition of the above objective values ​​tends to be minimized to obtain the optimal solution.

[0063] Target item for oxygen utilization The design is strongly related to the following factors: (1) Oxygen concentration on the flow battery side Improvement can accelerate the reaction rate, thereby reducing the charging voltage of the flow battery and reducing power consumption. The ideal target value of oxygen utilization is 95% to achieve engineering balance, so in the objective function optimization The closer the value is to 0, the better.

[0064] Weight coefficient: (with oxygen utilization rate as the priority), where For the optimization objectives of function M 、 、 The corresponding weight coefficients of the weight coefficients are 1 (i.e. α = 0.5, β = 0.3, γ = 0.2). Approaching 95% requires increasing compressor power consumption ( Increase), and the objective function Conflict, from the perspective of economic trade-off, in this application, by setting the weight , set the oxygen supply weight ratio to 50% (half), giving priority to ensuring oxygen utilization.

[0065] 3. Constraint Priority Mechanism (Safety First) The oxygen distribution is controlled by the variable (valve opening) and state variables (oxygen tank pressure) jointly determined.

[0066] (1) Flow battery oxygen concentration protection: ensure To maintain the reaction rate, if If the equipment is dangerous, it is mandatory to correct Improvement trend towards 0.8 (80% oxygen supply flow battery); (2) Minimum fuel cell utilization: ensuring oxygen utilization To prevent concentration polarization, if , which will damage the catalyst inside the fuel cell, so it is forced to correct Decrease towards 0.2 (80% oxygen supply to fuel cell); (3) Pressure safety: If , then forced correction Towards 1.0 (shutdown of fuel cell oxygen supply); (4) To ensure the oxygen tank pressure limit and maintain equipment safety, it is necessary to ensure ; (5) To avoid a single-channel oxygen flow rate that is too small, it is necessary to ensure that the oxygen distribution valve is open. .

[0067] To achieve the optimization of the objective function, the model predictive control (MPC) model for oxygen delivery optimization will be based on Figure 5 The distribution decision logic in the operation calculation is performed (this method is the optimal solution) and the final required oxygen distribution valve opening is output. , then press the output The oxygen amount is distributed according to the value.

[0068] Specifically, It is related to the oxygen flow rate allocated to the flow battery and fuel cell. will affect 、 、 The numerical value affects the value of the objective function M, and the calculated value of the objective function M is output in real time and fed back to the model MPC immediately, and then adjusted again. , the model MPC iteratively calculates the value of the objective function M again, and iterates repeatedly until the optimal value of M (when M is the minimum value) appears. The value is the optimal solution.

[0069] This allocation method simultaneously achieves three optimal goals: optimal oxygen utilization (optimal oxygen utilization by both the flow battery and fuel cell, resulting in the greatest energy efficiency gains); lowest oxygen production costs (partially produced using commercial valley electricity); and minimized losses during the production process. This minimizes oxygen supply costs while maximizing the overall energy efficiency of the coupled flow battery and fuel cell energy supply system.

[0070] In winter, the heating demand for the target building complex increases significantly. At this time, the hydrogen stored in the hydrogen storage unit 500 during the summer is released and used to supply hydrogen boilers for supplemental heating, SOFC fuel cells for power generation, and waste heat. This application utilizes hydrogen storage units 500 for cross-seasonal hydrogen storage, converting the large amount of excess summer solar energy into electrical energy and storing it across seasons for winter energy supply, thereby addressing the imbalance in solar power supply on a seasonal time scale.

[0071] In addition, wind energy resources are relatively abundant in winter. In the energy supply system, a large amount of surplus electricity generated by wind power generation units is stored in liquid flow batteries to perform daytime power peak regulation in the building park. The typical daily operation scheduling strategy of the energy system in each season can be found in the table below.

[0072] Typical daytime energy system operation table under each seasonal system

[0073] During the summer midday hours (12:00-15:00), solar radiation is strong, resulting in an excess of solar power generation. During this period, a large amount of electricity generated by the solar power generation units is used to electrolyze water to produce hydrogen, which is then stored in the hydrogen storage unit 500. Hydrogen molecules dissociate into hydrogen atoms on the surface of the magnesium-based material, which diffuse into the magnesium lattice to form solid granular magnesium hydride. The hydrogen storage density can reach 6.5wt% (i.e., 6.5 grams of hydrogen per 100 grams of material), significantly exceeding the volumetric hydrogen storage density of gaseous and liquid hydrogen. This storage takes the form of solid discs or granules, encapsulated in dedicated tanks, for long-term storage across seasons to ensure winter hydrogen supply. This method provides long-term, stable storage of hydrogen at room temperature and pressure, without the risk of leakage.

[0074] During winter, the SOFC operates at baseload power, while simultaneously releasing heat from the hydrogen boiler. Specifically, the SOFC generates electricity 24 hours a day at its rated load rate, while also generating waste heat at approximately 600°C. This means that the SOFC fuel cell's 24-hour operation generates a stable amount of electricity just enough to supply the building's critical power load. Furthermore, the high-temperature waste heat generated by the SOFC power generation (primary waste heat, 600°C) is first fed into a heating heat exchanger to produce steam or hot water for building heating. After cooling through heat exchange (secondary waste heat, 300°C), it is then used to preheat electrolytic water, thereby improving the efficiency of hydrogen production. If the steam or hot water generated by the SOFC waste heat is insufficient to meet the building's heating load, the hydrogen boiler is activated simultaneously, using the released hydrogen as a feedstock to generate steam and high-temperature hot water to supplement the insufficient heating demand. The hydrogen released from the hydrogen storage unit 500, which serves as the feedstock for the SOFC fuel cell and hydrogen boiler, must be released at a specific temperature and pressure. The addition of a catalyst (such as Ni, Fe, or carbon-based materials) can reduce the release temperature to 200-250°C. The high-temperature heat required for this reaction can be provided by secondary waste heat from the SOFC power generation (around 300°C). Furthermore, the system pressure must be controlled at 0.1-0.5 bar to accelerate hydrogen release. When the hydrogen storage level drops below 30%, the backup gas supply unit 910 is activated, switching to natural gas blending mode to ensure power continuity.

[0075] Of course, for safety reasons, a hydrogen storage capacity measuring instrument is provided in the hydrogen storage unit 500, and a hydrogen storage capacity safety percentage is set. When the hydrogen storage capacity is less than 30% (safety percentage), the hydrogen storage capacity measuring instrument flashes an alarm and starts the backup gas supply unit to perform the mixing mode, thereby ensuring the continuous supply of raw materials for SOFC power generation, maintaining stable and continuous power supply for SOFC, and ensuring the power supply safety of the building park.

[0076] In one embodiment, the flow battery is charged when its actual charge is less than 30% of its rated charge, and charging is stopped when its actual charge is greater than 80% of its rated charge. In practical applications, to balance lifespan and efficiency, the SOC (State of Charge) range of a flow battery is typically controlled between 20% and 95%. However, when the SOC exceeds 80%, side reactions are likely to occur, so charging time must be limited. When the SOC is less than 30%, concentration polarization may cause a sudden voltage drop, so deep discharge must be avoided. Taking these factors into consideration, this application sets the upper limit of the flow battery's SOC at 80% and the lower limit at 30%.

[0077] See also Figure 6 , this application adopts a central control system to control and monitor the parameters of each unit of the energy supply system. Each unit of the energy supply system and the input and output ends of the central control system are equipped with corresponding monitoring equipment and control equipment. As shown in the figure, E represents monitoring equipment, C represents control equipment, the wind power generation unit 310 is provided with E1 and C1, where E1 is the monitoring equipment of the wind turbine, and C1 is the control equipment of the wind turbine; the solar power generation unit 320 is provided with E2 and C2, where E2 is the monitoring equipment of photovoltaic power generation, and C2 is the control equipment of photovoltaic power generation; the energy storage peak regulation unit 200 is provided with E3 and C3, where E3 is the monitoring equipment of the liquid flow battery, and C3 is the control equipment of the liquid flow battery; the hydrogen storage unit 500 is provided with E4 and C4, where E4 is the monitoring equipment of the magnesium-based solid-state hydrogen storage device, and C4 is the control equipment of the magnesium-based solid-state hydrogen storage device; the hydrogen combustion heating unit 800 is provided with E5 and C5, among which E5 is the monitoring equipment of the hydrogen boiler, and C5 is the control equipment of the hydrogen boiler; the basic energy supply unit 100 is provided with E6 and C6, among which E6 is the monitoring equipment of the SOFC fuel cell, and C6 is the control equipment of the SOFC fuel cell; the standby power generation unit 900 is provided with E7 and C7, among which E7 is the monitoring equipment of the gas turbine, and C7 is the control equipment of the gas turbine.

[0078] Example 4: Continuous cloudy days (photovoltaic power generation <10%) The flow battery switches to "supply guarantee mode," raising the SOFC's lower limit load factor to 40% to prioritize critical loads. Hydrogen storage unit 500 releases hydrogen prematurely, boosting SOFC power to 100%, while the hydrogen boiler's heating power increases simultaneously. This means that when renewable energy generation is sufficient, the power supplied to the flow battery is also sufficient to meet the power requirements for fluctuating power loads. At this point, the SOFC only needs to operate stably at a low load factor (referred to as the operating lower limit load factor) to maintain a minimum safety baseline load for the target complex. During periods of continuous rain and overcast weather, the total power load of the target complex remains unchanged, but the flow battery's charge from renewable energy sources is significantly reduced, and the amount of power available to regulate fluctuating power loads for the target complex also drops sharply. In this case, the gap in fluctuating power loads must be made up by the power generation of SOFCs. Therefore, SOFCs can no longer simply provide a stable baseline power load. They must also increase the operating load rate, that is, raise the operating lower limit (the minimum load rate during operation). By increasing power generation, they can make up for the insufficient solar power generation due to continuous cloudy days and the insufficient power supply of liquid flow batteries to the fluctuating power loads of the target building complex.

[0079] Specifically, photovoltaic power generation is monitored in real time by the photovoltaic power generation monitoring device E2, battery SOC parameters are monitored in real time by the flow battery monitoring device E3, and SOFC load rate, power generation and other data are monitored in real time by the SOFC monitoring device E6.

[0080] When continuous cloudy days cause photovoltaic power generation monitoring device E2 to detect real-time photovoltaic output below 10% (10% of the photovoltaic panel's maximum generating capacity), and the weather forecast confirms no sunlight restoration within the next 24 hours, the SOFC's minimum generating load must be increased to 40% to ensure the target building complex's base load. At this point, the central control system issues a command to the energy storage peak-shaving unit 200, hydrogen storage unit 500, and basic energy supply unit 100, corresponding to control devices C3, C4, and C6, respectively, to activate "supply guarantee mode." Upon receiving the command, control device C3 of the energy storage peak-shaving unit 200 increases the flow battery's SOC operating limit from 30% to 40%, enabling the flow battery to deliver power to critical load circuits (such as data centers and hospitals). Control device C4 of the hydrogen storage unit 500 initiates an emergency hydrogen release to ensure sufficient SOFC fuel. Control device C6 of the basic energy supply unit 100 receives commands from the central control system and gradually increases power generation from 60% to 100%, with a response time of ≤3 minutes. Control device C5 of the hydrogen combustion heating unit 800, based on SOFC exhaust temperature (>600°C) monitored by E6 and the target building complex's heating demand, gradually increases power generation from 50% to 80% to meet the building complex's heating needs.

[0081] Example 5: Storm causes excessive wind power generation During wind power generation, excess electricity is used for electrolysis to produce hydrogen, and the power of the hydrogen storage unit 500 is dynamically adjusted (50%-100%). When the SOC of the flow battery exceeds the limit, the wind curtailment protection is activated to limit the output of the wind turbine.

[0082] Specifically, the central control system uses monitoring device E1 of the wind power generation unit 310 to collect parameters such as wind turbine output power, wind speed, and rotational speed. It also uses monitoring device E3 of the energy storage peak-shaving unit 200 to obtain real-time flow battery SOC (State of Charge) data and set upper and lower thresholds (SOC-max = 80%, SOC-min = 30%). When monitoring device E3 of the energy storage peak-shaving unit 200 detects that the real-time SOC exceeds SOC-max (overcharge), it sends an alarm signal to the wind power generation unit's control system, triggering the wind curtailment protection logic. Monitoring device E3 of the wind power generation unit transmits the real-time battery SOC data to the central control system. The central control system, combined with real-time data such as wind turbine wind speed, rotational speed, and output power transmitted by monitoring device E1, transmits a wind turbine speed adjustment command to control device C1 of the wind power generation unit 310. This reduces the wind turbine speed, thereby reducing the charging power output from the wind power generation unit 310 to the energy storage peak-shaving unit 200 (at this point, the charging power is reduced to 0), thereby preventing the battery SOC from exceeding the limit during a storm. Monitoring device E3 in the energy storage peak-shaving unit 200 continuously monitors changes in the SOC. If the SOC drops to 80% within 30 minutes, the wind turbine output is gradually restored to 90% of its original limit. If the SOC does not decrease, C1 is used to further limit the wind turbine speed until the wind turbine output drops to 60% to ensure the battery SOC decreases. When the SOC returns to a safe range (e.g., SOC ≤ 80%), the central control system removes the power limit command, and the wind turbine resumes normal operation.

[0083] Example 6: Equipment failure (such as SOFC shutdown) The flow battery switches to baseload mode (maintaining a SOC of 60%-80%); the hydrogen boiler temporarily replaces the SOFC waste heat supply, and the backup power generation unit 900 is activated. Baseload mode, in this context, refers to a power supply mode that ensures base load. This means that when the SOFC is shut down, the backup power generation unit 900 (gas turbine) requires time to start up. During the period when the backup gas turbine has started but is not generating electricity, or when startup takes a long time, the flow battery will provide the minimum baseline safety power for the target building complex. If the SOFC monitoring equipment detects a sudden drop in SOFC output voltage (<10% of rated load for 10 seconds), a hydrogen supply interruption, or an SOFC stack temperature exceeding the limit (stack temperature >950°C or <600°C for 1 minute), the central control system automatically determines that the SOFC is in a fault state, initiates a shutdown alarm signal, and immediately sends a command to the flow battery control device C3 to switch to baseload mode. C3 adjusts the flow battery's SOC operating range from free charge and discharge to a constant 60%-80% range, prioritizing the supply of baseload power. (During the period when the backup gas turbine is not generating electricity, the baseload power is provided by the flow battery.) Simultaneously, the central control system issues startup commands to the hydrogen boiler and backup gas turbine control devices C5 and C7. The hydrogen boiler temporarily replaces the SOFC waste heat supply, and the backup gas turbine replaces the SOFC power supply. To protect the safe operation of the hydrogen boiler, if the hydrogen boiler monitoring device E5 detects that the hydrogen boiler outlet temperature exceeds 150°C, an emergency hydrogen boiler shutdown is triggered through the central control system.

[0084] The flow battery of the energy supply system in this application adopts the following dynamic capacity configuration method during daytime peak load regulation: The state of charge (SOC) range is optimized based on the peak-valley price difference (e.g., 1.2 yuan / kWh during peak hours and 0.3 yuan / kWh during valley hours). The SOC is increased to 80% during the charging period (valley hours) and reduced to 30% during the discharging period (peak hours). Its response time is ≤ 1 second, which can smooth out photovoltaic fluctuations (e.g., a 10% power drop caused by cloud cover).

[0085] In terms of life management, the charge and discharge depth of the flow battery is limited to 80%, and the number of cycles can be increased to 15,000 times; at the same time, an electrolyte balance cycle is performed once a month to prevent ion cross contamination.

[0086] The functional system and operation control method of this application have the following advantages: 1. SOFC waste heat is utilized in stages with high utilization rate Winter mode: The first-level waste heat (600°C) is used for indoor heating, improving energy efficiency by 30%; the second-level waste heat (300°C) is used to preheat electrolyzed water to 60°C, reducing hydrogen production energy consumption by 15%.

[0087] Summer mode: The first-level waste heat drives an absorption chiller (COP=1.3), replacing the electric air conditioner; the second-level waste heat is stored in the heat storage unit 700 (using paraffin, melting point 50°C) and used to preheat the flow battery electrolyte. Moderate preheating of the flow battery electrolyte (30°C-50°C) can improve the energy efficiency of the flow battery (5%-12%).

[0088] 2. Wide range of applications (with examples) (1) Industrial Park Industrial parks typically require a continuous and stable power supply, as well as industrial steam or hot water (e.g., chemical, pharmaceutical, and food processing companies). SOFCs can directly utilize industrial byproduct hydrogen or natural gas to generate electricity, while also generating high-temperature waste heat (400-600°C) that can be converted into steam for production use.

[0089] (2) Data center room Data centers require a stable 24 / 7 power supply, and their servers have high cooling requirements (cooling load accounts for approximately 40%). Electricity costs account for 30%-50% of data center costs. This energy supply system, leveraging the difference in peak and off-peak electricity prices, can save 20%-30% by storing hydrogen during off-peak hours and using it during peak hours.

[0090] (3) Hospital buildings: Hospitals require uninterrupted power supply (for operating rooms, ICUs, etc.) and large quantities of hot water (for disinfection and heating). SOFC waste heat can be directly used for hot water production or district heating, increasing overall energy efficiency to over 85%.

[0091] (4) Large commercial parks: Large commercial complexes often have a relatively large number of hotels, which require a large amount of hot water load all year round (hotel bathing, hotel item cleaning and disinfection, etc.), and the electricity demand fluctuates greatly (peak during the day). SOFC is combined with liquid flow batteries to achieve intraday peak regulation, waste heat cooling in summer, heating or hot water supply in winter, and the commercial electricity price has a large peak-to-valley difference (1.2 yuan / kWh during peak hours). The comprehensive energy cost can be reduced by about 25% through valley electricity hydrogen storage and waste heat utilization.

[0092] 3. High returns on energy supply system Through the coordinated regulation of the "seasonal-intraday" dual time scale and the coupled optimization of the "heat-electricity-hydrogen" multi-energy flow, the energy supply system can achieve the following benefits: (1) Economic efficiency: Liquid flow batteries can store hydrogen during valley hours and use it during peak hours to save electricity costs. Hydrogen energy storage for cross-seasonal peak shaving can reduce electricity purchase costs by 40%; according to rough estimates, when the commercial electricity price is less than 0.5 yuan / kWh and the peak electricity price is greater than 1.2 yuan / kWh, the liquid flow battery peak-valley shaving and valley electricity hydrogen production energy supply system can achieve profitability. (2) Reliability: Power supply availability in extreme weather is ≥99.9%, and the waste heat of SOFC can guarantee the heat demand of buildings. (3) Environmental protection: The carbon emission reduction effect is significant throughout the year, and the proportion of green hydrogen exceeds 70%.

[0093] The technical features of the above-described embodiments may be combined in any manner. To simplify the description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as no contradiction exists between these combinations of technical features, they should be considered to be within the scope of this specification. When technical features of different embodiments are embodied in the same drawing, it can be deemed that the drawing also discloses examples of combinations of the various embodiments involved.

[0094] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present application, and such modifications and improvements are all within the scope of protection of the present application.

Claims

1. A fuel cell coupled flow battery energy supply system, characterized in that: include: A basic energy supply unit that uses fuel cells to generate electricity to meet the basic power load of the target building complex; Energy storage peak shaving units, which use flow battery energy storage to meet the fluctuating power loads of the target building complex; a renewable energy power generation unit that utilizes renewable energy to generate electricity for water electrolysis or storage in the flow battery; an electrolysis hydrogen production unit that utilizes electricity generated by a renewable energy power generation unit to electrolyze water to produce hydrogen; A hydrogen storage unit, which is used to store hydrogen and release hydrogen in a timely manner for the fuel cell to generate electricity; a primary waste heat recovery unit, which receives the primary waste heat generated by the fuel cell for indoor heating or indoor cooling of the target building complex; A secondary waste heat recovery unit, which directly receives the primary waste heat generated by the fuel cell power generation or the secondary waste heat from the primary waste heat recovery unit, and is used for preheating the water electrolysis and / or hydrogen storage unit; The heat storage unit is used to store the primary waste heat generated by the fuel cell power generation or the secondary waste heat from the primary waste heat recovery and utilization unit.

2. The energy supply system according to claim 1, characterized in that: The flow battery is preheated using waste heat stored in the heat storage unit.

3. The energy supply system according to claim 1, characterized in that: The renewable energy power generation unit includes a wind power generation unit and a solar power generation unit.

4. The energy supply system according to claim 1, characterized in that: It includes a hydrogen combustion heating unit for indoor heating of the target building complex.

5. The energy supply system according to claim 1, characterized in that: It includes a backup power generation unit, which can generate electricity to meet the basic power load of the target building complex when the basic power supply unit is shut down.

6. The energy supply system according to claim 1, characterized in that: An oxygen storage unit is included, which is used to store oxygen and release oxygen to supply the fuel cell and / or liquid flow battery to participate in oxidation reaction.

7. The operation control method of the energy supply system according to any one of claims 1 to 5, characterized in that: include: Fuel cell power generation meets the basic power load of the target building complex, and flow batteries supplement the power load gap during peak hours; The waste heat generated by fuel cell power generation is used for one or more of indoor cooling, indoor heating, preheating electrolyzed water, preheating hydrogen storage units, and storing in heat storage units according to seasonal conditions; The electricity generated by the renewable energy power generation unit is first stored in the energy storage peak-shaving unit, and the excess electricity is used to electrolyze water to produce hydrogen.

8. The operation control method of the energy supply system according to claim 7, characterized in that: In summer, the primary waste heat generated by fuel cell power generation first meets the indoor cooling needs of the target building complex, and the secondary waste heat is stored in the heat storage unit; In winter, the primary waste heat generated by fuel cell power generation is first used to meet the indoor heating needs of the target building complex, and the secondary waste heat is used to preheat the electrolyzed water and / or hydrogen storage unit; In spring and autumn, the primary waste heat generated by fuel cell power generation is directly used to preheat the electrolyzed water and / or hydrogen storage unit, and the remaining part is stored in the heat storage unit.

9. The operation control method of the energy supply system according to claim 7, characterized in that: When the actual power of the flow battery is less than 30% of the rated power, it is charged. When the actual power of the flow battery is greater than 80% of the rated power, charging is stopped.

10. The operation control method of the energy supply system according to claim 7, characterized in that: It includes an oxygen storage unit, which is used to store oxygen and release oxygen to supply the fuel cell and / or liquid flow battery to participate in the oxidation reaction. According to the following prediction function, the oxygen distribution valve opening is obtained , , when the M value is the minimum, the corresponding That is the optimal solution for oxygen distribution; Prediction function for optimal oxygen delivery: in, , is the oxygen utilization rate, is the oxygen concentration in the cathode cavity of the flow battery (mol / m³), is the oxygen utilization rate of the fuel cell cathode (%); is the relative saturation concentration of oxygen in the flow battery; is the energy cost of oxygen production, is the power of the oxygen production system, is the electricity price at that time; To quantify the life loss cost of oxygen compressors, is the compressor speed, is the relative speed; α, β, and γ are weight coefficients, α=0.5, β=0.3, and γ=0.2.

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