System flexibility margin calculation method based on electro-hydrogen coupling

Abstract

The invention relates to a system flexibility margin calculation method based on electricity-hydrogen coupling, and provides an electricity-hydrogen multi-node bidirectional coupling micro-grid flexibility margin optimization scheduling method for solving the problems of system inertia reduction and anti-interference capability weakening caused by high-proportion new energy access to a power grid. Firstly, a practical and operable electro-hydrogen coupling multi-node system model is constructed, and secondly, the economical efficiency of the system is comprehensively evaluated. According to the method, on the basis of an electricity-hydrogen multi-node bidirectional coupling regional micro-grid system and demand prediction of day-ahead wind-solar power generation output and load, electricity-hydrogen coupling output is optimized by adopting a multi-objective optimization algorithm with the goal of minimizing the overall operation cost of the micro-grid, and day-ahead optimal global regional micro-grid scheduling is realized; and according to an optimization result, performing energy supply analysis under different node scenes, and comparing flexibility margins among different devices through a normalization algorithm.

Description

Technical Field

[0001] The present invention relates to a margin calculation method, and in particular to a system flexibility margin calculation method based on electric-hydrogen coupling for evaluating the development of electric-hydrogen coupling technology, thereby better judging and predicting future technology development trends. Background Art

[0002] With the rapid development of renewable energy (such as wind and solar) around the world, the volatility and uncertainty of the energy system have increased significantly. Traditional power systems are difficult to cope with these fluctuations and uncertainties due to the lack of sufficient flexibility. This has led to an increase in the demand for system flexibility to ensure the stability and security of power supply.

[0003] As a clean and efficient secondary energy source, hydrogen energy has high energy density and diverse application scenarios, and is considered to be one of the important means to achieve energy system flexibility. The electric-hydrogen coupling system can convert electricity into hydrogen energy storage when there is excess electricity, and supplement electricity demand through hydrogen power generation when there is a shortage of electricity, thereby achieving flexible conversion and regulation between electricity and hydrogen energy.

[0004] However, the current electric-hydrogen coupling system still has room for optimization in terms of flexibility and efficiency. There is a deviation between actual operation and related theoretical research. The latter is mainly based on a single flexibility resource and lacks comparison of different flexibility resources. How to effectively optimize the operation strategy of the electric-hydrogen coupling system to maximize the system's flexibility margin while improving the system's overall efficiency has become an urgent problem to be solved. Summary of the invention

[0005] In view of the above problems, the main purpose of the present invention is to provide a method for calculating the system flexibility margin based on electric-hydrogen coupling to solve the evaluation of the development of electric-hydrogen coupling technology, so as to better judge and predict the future technology development trend.

[0006] The present invention solves the above technical problem through the following scheme: a method for calculating system flexibility margin based on electric-hydrogen coupling, the method for calculating system flexibility margin based on electric-hydrogen coupling comprising the following steps:

[0007] (1) Establish a mathematical model of the electric-hydrogen coupled multi-node system, including a water electrolysis hydrogen production module, a hydrogen storage module, and a fuel cell power generation module;

[0008] (2) Establish a flexibility margin model for electricity-hydrogen coupling, including flexible power sources on the load side and flexible power sources on the source side;

[0009] (3) Establish a total cost calculation model for the entire life cycle of the electric hydrogen system, including initial equipment investment cost, equipment operation and maintenance cost, total operating cost, total economic benefit, net profit calculation model and constraints;

[0010] (4) Iteratively optimize the configuration of the electric hydrogen system based on the PSO algorithm to achieve the optimal solution;

[0011] (5) Normalize the equipment in the system to achieve the universality of flexibility margin analysis under different equipment capacity conditions.

[0012] In a specific implementation example of the present invention, the energy supply equipment in the system in step (1) includes various generator sets, renewable energy units, and hydrogen power generation equipment. The energy storage module in the system includes batteries and hydrogen storage tanks. The system energy users include users of different power nodes, electrolyzers, and battery equipment. The hydrogen fuel cell is an important source of electricity in the system, and the electrolyzer is the main source of hydrogen energy in the system. The important coupling element for realizing electric-hydrogen conversion utilizes hydrogen energy and its related energy equipment to realize the coupling of different energy forms, which can enhance the complementary coordination between different energy forms in the system and form a highly flexible multi-energy complementary system.

[0013] In a specific implementation example of the present invention, based on an electric-hydrogen multi-node system, a flexibility margin calculation method under an electric-hydrogen multi-node is proposed.

[0014] In a specific implementation example of the present invention, a mathematical model of an electric-hydrogen multi-node system is constructed, including various energy conversion forms such as wind power generation, photovoltaic power generation, water electrolysis to produce hydrogen, hydrogen storage, and fuel cell power generation, involving energy types such as electricity and hydrogen, to achieve flexible conversion and regulation of the energy system.

[0015] In a specific implementation example of the present invention, a flexible margin optimization model is constructed, a mathematical model of flexibility supply and demand is defined, the characteristics of flexibility resources are considered, and flexibility resources are comprehensively evaluated and optimized from multiple angles and multiple levels to improve the overall efficiency of the system.

[0016] In a specific implementation example of the present invention, a calculation model for the total cost, total revenue and net profit of the system's entire life cycle is constructed, including initial equipment investment cost, operation and maintenance cost, total operating cost, total economic benefit and net profit calculation model, to comprehensively evaluate the economic efficiency of the system.

[0017] In a specific implementation example of the present invention, a PSO-based multi-objective optimization algorithm is used to optimize the configuration of the electrolytic cell capacity, the hydrogen storage tank capacity and the fuel cell capacity.

[0018] In a specific implementation example of the present invention, the mathematical modeling of the electric-hydrogen coupled multi-node system includes:

[0019] (1) Wind power generation system

[0020] The wind turbine output is related to the wind speed, and its probability density expression for wind speed v is:

[0021] Where: Γ is the gamma function; c is the amplitude coefficient; k is the scale coefficient; σ and μ are the standard deviation and sample mean of v, respectively.

[0022] The mathematical expression of the output of a single fan and the wind speed is:

[0023]

[0024] Where: v t is the actual wind speed; v in is the cut-in wind speed; v out is the cut-out wind speed; v r Refers to the rated wind speed; p wtr Refers to the rated output power; P wt (t) refers to the actual output power of the fan;

[0025] In a specific implementation example of the present invention, the mathematical modeling of the electric-hydrogen coupled multi-node system also includes: Photovoltaic power generation system: In order to reduce errors by considering the actual situation, the actual output power of the photovoltaic cell is related to the solar radiation intensity and the ambient temperature, so its mathematical expression is:

[0026]

[0027] η loss (t) = 1 + λ (T (t) - 25) (1-4)

[0028]

[0029] Where: C PV is the rated power of the photovoltaic cell; S (t) is the light intensity at time t; S ST is the standard light intensity; η pv_DC-DC is the photovoltaic power exchange efficiency; η loss is the power loss of the photovoltaic cell; λ is the temperature coefficient, which can be taken as; T(t) is the operating temperature of the equipment; T a (t) is the actual ambient temperature; T N is the standard temperature;

[0030] In a specific implementation example of the present invention, the mathematical modeling of the electric-hydrogen coupled multi-node system also includes: electric-hydrogen coupled system: when the wind and solar output power is greater than the power demand in the park, the electrolyzer starts working to convert the surplus electricity into hydrogen energy, and stores the excess hydrogen in the hydrogen storage tank; when the wind and solar resources are insufficient to supply the demand, the hydrogen stored in the hydrogen storage tank will be used as fuel cell fuel for power generation.

[0031] The positive progress of the present invention is that compared with the common similar technologies, the system flexibility margin calculation method based on electric-hydrogen coupling provided by the present invention has the following advantages:

[0032] (1) The flexibility margin calculation method of electric hydrogen multi-node is of great significance in the case of high renewable energy access. At present, there is a gap between the research on the flexibility margin of the electric hydrogen system and the actual system operation. The current research mainly focuses on power balance processing and lacks a specific analysis of system flexibility. The present invention is based on the electric hydrogen multi-node system and proposes a flexibility margin calculation method under the electric hydrogen multi-node.

[0033] (2) The present invention constructs a mathematical model of an electric-hydrogen multi-node system, including various energy conversion forms such as wind power generation, photovoltaic power generation, water electrolysis to produce hydrogen, hydrogen storage, and fuel cell power generation, involving energy types such as electricity and hydrogen, to achieve flexible conversion and regulation of the energy system.

[0034] (3) The present invention constructs a flexibility margin optimization model, defines a mathematical model of flexibility supply and demand, considers the characteristics of flexibility resources, comprehensively evaluates and optimizes flexibility resources from multiple angles and multiple levels, and improves the overall efficiency of the system. The model also emphasizes the balance and normalization of flexibility supply and demand, solves the problems of reduced system inertia and weakened anti-interference ability caused by high proportion of new energy access, and provides a highly adaptable microgrid flexibility margin optimization scheduling method.

[0035] (4) The present invention further constructs a calculation model for the total cost, total revenue and net profit of the system throughout its life cycle, including the initial equipment investment cost, operation and maintenance cost, total operating cost, total economic benefit and net profit calculation model, to comprehensively evaluate the economic efficiency of the system.

[0036] (5) The present invention adopts a PSO-based multi-objective optimization algorithm to optimize the configuration of the electrolytic cell capacity, hydrogen storage tank capacity and fuel cell capacity. The goal is to minimize the overall operating cost of the microgrid, maximize the system net profit, achieve the optimal configuration of the electric-hydrogen coupling system, and improve the flexibility of the system and the overall operating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a flow chart of the method for calculating the flexibility margin of the electric hydrogen system of the present invention.

[0038] Figure 2 The multi-node integrated energy system of the present invention

[0039] Figure 3 This is a capacity optimization flow chart of the present invention. DETAILED DESCRIPTION

[0040] Preferred embodiments of the present invention are given below in conjunction with the accompanying drawings to illustrate the technical solutions of the present invention in detail.

[0041] Figure 1 Flow chart of the method for calculating the flexibility margin of the electric hydrogen system of the present invention. Figure 1 As shown: The problem to be solved by the present invention is the reduction of system inertia and weakened anti-interference ability caused by the high proportion of new energy access to the power grid, and a method for optimizing the flexibility margin scheduling of a microgrid with electric-hydrogen multi-node bidirectional coupling is provided. The first is to construct a practical and operable electric-hydrogen coupling multi-node system model, and the second is to make a comprehensive evaluation of the economic efficiency of the system.

[0042] The present invention is based on a regional microgrid system with multi-node bidirectional coupling of electricity and hydrogen, and based on the forecast of the demand for wind and solar power generation output and load in the previous day, with the goal of minimizing the overall operating cost of the microgrid. A multi-objective optimization algorithm is used to optimize the electricity-hydrogen coupling output, and the optimal global regional microgrid scheduling in the previous day is achieved. According to the optimization results, energy supply analysis is performed in different node scenarios, and the flexibility margin between different devices is compared through a normalization algorithm.

[0043] The main steps include:

[0044] (1) Establish a mathematical model of the electric-hydrogen coupled multi-node system, including a water electrolysis hydrogen production module, a hydrogen storage module, and a fuel cell power generation module.

[0045] (2) Establish a flexibility margin model for electricity-hydrogen coupling, including flexible power sources on the load side and flexible power sources on the source side.

[0046] (3) Establish a total cost calculation model for the entire life cycle of the electric hydrogen system, including the initial equipment investment cost, equipment operation and maintenance cost, total operating cost, total economic benefit, net profit calculation model and constraints.

[0047] (4) Iteratively optimize the electric hydrogen system configuration based on the PSO algorithm to achieve the optimal solution.

[0048] (5) The equipment in the system is normalized to achieve the universality of flexibility margin analysis under different equipment capacity conditions.

[0049] 1. Modeling of electric-hydrogen coupled multi-node system:

[0050] (1) Electric-hydrogen coupled multi-node system

[0051] A multi-node integrated energy system with hydrogen as a flexible energy source involves various energy conversion forms such as electrolysis hydrogen production, hydrogen storage, and hydrogen-to-electricity. The system includes a variety of equipment such as energy transmission, conversion, and energy storage equipment, covering energy types such as electricity and hydrogen. Figure 2 As shown, the numbers represent microgrids with different voltage nodes. Different microgrids are coupled with multiple nodes through power-to-hydrogen, hydrogen-to-electricity, electricity-to-electricity and other methods to achieve energy flow complementarity.

[0052] The main energy supply equipment in the system includes various generator sets, renewable energy units (photovoltaic generator sets, wind turbines, etc.), and hydrogen power generation equipment (hydrogen-fired turbines, hydrogen fuel cells, hydrogen internal combustion engines, hydrogen-fired boilers, etc.). The main energy storage equipment in the system includes batteries, hydrogen storage tanks, etc., which can effectively improve the safety and reliability of system operation. The system mainly uses users with different power nodes, electrolyzers, and battery equipment. Among them, hydrogen fuel cells are an important source of electricity in the system, and electrolyzers are the main source of hydrogen energy in the system. The two are important coupling elements for realizing electricity-hydrogen conversion. Using hydrogen energy and its related energy equipment to achieve coupling of different energy forms can strengthen the complementary coordination between different energy forms in the system and form a highly flexible multi-energy complementary system.

[0053] (2) Mathematical modeling of the electric-hydrogen coupled multi-node system

[0054] 1. Wind power generation system

[0055] The wind turbine output is related to the wind speed, and its probability density expression for wind speed v is:

[0056]

[0057] Where: Γ is the gamma function; c is the amplitude coefficient; k is the scale coefficient; σ and μ are the standard deviation and sample mean of v, respectively.

[0058] The mathematical expression of the output of a single fan and the wind speed is:

[0059]

[0060] Where: v t is the actual wind speed; v in is the cut-in wind speed; v out is the cut-out wind speed; v r Refers to the rated wind speed; p wtr Refers to the rated output power; P wt (t) refers to the actual output power of the fan.

[0061] 2. Photovoltaic power generation system

[0062] In order to reduce the error by considering the actual situation, the actual output power of the photovoltaic cell is related to the solar radiation intensity and the ambient temperature, so its mathematical expression is:

[0063]

[0064] η loss (t) = 1 + λ (T (t) - 25) (1-4)

[0065]

[0066] Where: C PV is the rated power of the photovoltaic cell; S (t) is the light intensity at time t; S ST is the standard light intensity; η pv_DC-DC is the photovoltaic power exchange efficiency; η loss is the power loss of the photovoltaic cell; λ is the temperature coefficient, which can be taken as λ; T(t) is the operating temperature of the equipment; Ta(t) is the actual ambient temperature; TN is the standard temperature.

[0067] 3. Electricity-hydrogen coupling system

[0068] When the wind and solar power output is greater than the power demand in the park, the electrolyzer starts working to convert the surplus electricity into hydrogen energy and store the excess hydrogen in the hydrogen storage tank; when the wind and solar resources are not enough to meet the demand, the hydrogen stored in the hydrogen storage tank will be used as fuel cell fuel for power generation to meet user needs.

[0069] ①Electrolyzer

[0070] The electrolytic cell consists of a cell body, an anode and a cathode, and most of them are separated by a diaphragm to separate the anode chamber from the cathode chamber. When direct current passes through the electrolytic cell, an oxidation reaction occurs at the interface between the anode and the solution, and a reduction reaction occurs at the interface between the cathode and the solution to produce the desired product.

[0071] The output power of the electrolyzer can be expressed as:

[0072] P el-tank =P el η el (1-6)

[0073] Where: P el is the input power; el For equipment efficiency.

[0074] ②Hydrogen storage tank

[0075] A hydrogen storage tank is a container for storing and releasing hydrogen energy. It is composed of alloy powder, heat exchange components, gas transmission components and tank materials. Considering the unstable characteristics of hydrogen, the main material is usually stainless steel for safety.

[0076] The mathematical model of hydrogen storage tank energy storage can be expressed as:

[0077]

[0078] Where: E tank (t) is the energy stored in the hydrogen storage tank at time t; E tank (t-1) is the energy stored in the hydrogen storage tank at time (t-1); η el_DC-DC , η fc_DC-DC are the efficiencies of the electrolyzer and fuel cell, respectively; η tank is the efficiency of the hydrogen storage tank.

[0079] ③ Fuel Cell

[0080] A fuel cell is a power generation device that can directly convert the chemical energy of fuel and oxidant into electrical energy through electrochemical reactions. It is mainly composed of four parts: anode, cathode, electrolyte and external circuit. Fuel gas and oxidant gas are introduced into the anode and cathode of the fuel cell respectively. The fuel gas releases electrons at the anode, which are conducted to the cathode through the external circuit and combined with the oxidant to form ions. Under the action of the electric field, the ions migrate to the anode through the electrolyte, react with the fuel gas, form a circuit, and generate current.

[0081] The fuel cell model selects the proton exchange membrane fuel cell and its output power is:

[0082] P fc =P tank-fc η fc (1-8)

[0083] Where: P tank-fc The power input from the hydrogen tank to the fuel cell: η fc The efficiency of fuel cell operation.

[0084] 2. Flexibility Margin Model

[0085] The flexibility within the node refers to the ability of the system to cope with load fluctuations and the uncertainty of renewable energy by dispatching various types of flexible resources within a certain time scale. The complete power system flexibility should include indicators of multiple aspects such as source, grid, load and storage. However, at present, relatively complete quantitative evaluation indicators of flexibility are often not practical and operational at this stage. Therefore, the present invention focuses on the normalization of flexibility margin, and proposes a universal power supply flexibility margin indicator and its normalized calculation method from the perspective of flexibility supply and demand balance. From the perspective of flexibility analysis, loads such as electricity-to-hydrogen and batteries (electricity storage) can be regarded as "flexible power sources" on the load side. Similarly, hydrogen-to-electricity and batteries (discharge) can also be regarded as flexible power sources on the source side.

[0086] (1) Flexible resource supply

[0087] The situations of responding to the increase and decrease of system load are called upward flexibility and downward flexibility supply respectively, which can be expressed as:

[0088]

[0089]

[0090]

[0091] Where:

[0092] To increase the flexibility supply of the representative equipment K in time period t; To represent equipment K, adjust the flexibility supply downward in time period t; is the maximum operating power of the representative device k; is the minimum operating power of the representative device k; represents the actual operating power of the equipment during the time period t; R mk is the system ramp rate of the Kth type of flexibility resource. i represents the i-th moment of system operation; K represents different devices in the system; θ is the ramp rate; P i is the rated load of the electrolyzer.

[0093] (2)Flexibility resource requirements

[0094] The system flexibility demand is derived from the regularity of user loads and the volatility and uncertainty of renewable energy. In view of the increase and decrease of load and fluctuations on the source side, the upward and downward flexibility demands are:

[0095]

[0096]

[0097] Where:

[0098] ω + (t),ω - (t): total flexibility demand at time t, adjusted up / down; The positive / negative photovoltaic predicted fluctuation at time t; ——The predicted positive / negative wind power fluctuation at time t; The predicted fluctuation of positive / negative electric load at time t.

[0099] (3) Flexibility margin

[0100] The flexibility margin index is defined as the difference between flexibility supply and flexibility demand, so the upward and downward flexibility margins can be expressed as:

[0101]

[0102]

[0103] Where:

[0104] F up 、F down The flexibility margin is adjusted upward and downward for the system. When the flexibility of the system is insufficient, the system will face the risk of wind and solar power abandonment; when the flexibility of the system is insufficient, the system will face the risk of load shedding.

[0105] Energy storage link:

[0106] Energy storage equipment is an important energy supply and regulation equipment. The main energy storage equipment includes electric energy storage equipment, hydrogen energy storage equipment, etc. Different types of energy storage equipment have the same charging and discharging principles. The energy storage equipment model can be uniformly expressed as:

[0107]

[0108] Where: k represents different energy storage devices (hydrogen storage tanks, batteries, etc.); E k，t 、E k，t-1 Represents the energy storage capacity at time t and time t+1; δ k，loss Represents the energy storage loss of the energy storage device; μ k，ch , μ k，d Represents the charging efficiency and discharging efficiency of the equipment.

[0109] 3. System Life Cycle Calculation

[0110] (1) System initial equipment investment cost calculation model

[0111] According to the set operation mode, the total one-time investment cost of the equipment is F0, which mainly includes the cost of solar photovoltaic panels F pv , wind turbine cost F w 、Hydrogen production device F H 、Electricity storage device F e 、Hydrogen storage device F HC 、Hydrogen to electricity device F Hd .

[0112] F0=F pv +F w +F H +F e +F HC +F Hd (3-1)

[0113] The relationship between the initial total investment of each equipment and its equipment scale is as follows:

[0114] Fk =m k P k (3-2)

[0115] Where:

[0116] P k is the rated planned installed capacity of the equipment, kW; m k is the unit capacity cost of the equipment, RMB 10,000 / kW; k represents the equipment in the system.

[0117] (2) System equipment operation and maintenance cost calculation model

[0118] The operation and maintenance costs of the entire project life cycle mainly include the daily maintenance costs of each equipment and the equipment replacement costs.

[0119] F r =F pur +F wr +F Hr +F er +F HCr +F Hdr (3-3)

[0120] Where:

[0121] F pvr F is the operation and maintenance cost of photovoltaic power generation equipment throughout its life cycle; wr F is the operation and maintenance cost of wind power equipment throughout its life cycle; Hr F is the operation and maintenance cost of the hydrogen production equipment throughout its life cycle; er F is the operation and maintenance cost of the energy storage equipment throughout its life cycle; HCr F is the operation and maintenance cost of the hydrogen storage equipment throughout its life cycle; Hdr It is the operation and maintenance cost of the hydrogen-to-electricity equipment throughout its entire life cycle.

[0122] The cost of each part can be estimated by its percentage of the initial investment of the project. As follows:

[0123]

[0124] In the formula: K represents each device in the system; J is the equipment operation and maintenance coefficient; l is the discount rate, generally 5%; n is the full life cycle of the system.

[0125] (3) Mathematical model of total operating cost of the system throughout its life cycle

[0126] Combining the operating cost and initial investment cost, the mathematical model of the total cost of the system throughout its life cycle can be obtained:

[0127]

[0128] Where:

[0129] F total is the cumulative total operating cost in year t.

[0130] (4) Mathematical calculation model of total economic benefits of the system throughout its life cycle

[0131] Based on the operation mode set in Section 1, the economic benefits of this system include the income from the sale of electricity from renewable energy grid-connected power generation, the income from hydrogen sales, and the income from the grid-connected power generation equipment. The total economic benefits of the system are E total :

[0132] (3-14)

[0133] Where:

[0134] E k - Revenue from grid-connected electricity sales from renewable energy; E H - Revenue from hydrogen sales; E e - Income from grid connection of controllable power generation equipment; E e0 ——Expenditures on electricity purchase; E c ——Penalty for abandoning power.

[0135] (5) Net profit calculation model for the system’s entire life cycle

[0136] The net profit of the system is equal to the difference between the total economic benefits and the total cost of the system throughout its life cycle. The total income also includes the conversion of the residual value of each device during the entire life cycle. Therefore, the net profit F S :

[0137]

[0138] Where:

[0139] L t ——The residual value of each part of the system equipment in the tth year is calculated at 5% of the fixed assets;

[0140] r1 – discount rate, calculated as a fixed value of 10%.

[0141] (6) Constraints

[0142] The energy balance is shown in the following formula:

[0143] (1) Electric power balance constraints

[0144] P pv +P w +P ou +P ie =P fh +P ih +P a (3-7)

[0145] Where:

[0146] P ou Purchase electricity from external power grid; P ie Provide power for hydrogen power generation equipment; ih P is the electric power load of the electric hydrogen production equipment; fh is the electrical load; P a To abandon wind and electricity.

[0147] (2) Wind power and photovoltaic power

[0148] Stable operation constraints of wind turbines and photovoltaic generators:

[0149] P wmin ≤P W ≤P wmax (3-8)

[0150] P vmin ≤P v ≤P vmax (3-9)

[0151] Where:

[0152] P wmin , P wmax is the minimum and maximum output of the fan; P vmin , P vmax It is the minimum and maximum output of photovoltaic.

[0153] (3) Electrolysis hydrogen production equipment

[0154]

[0155] P fc，min ≤P fc ≤P fc，max (3-11)

[0156] Where:

[0157] and It is the upper and lower limits of the electrolytic cell operating power. fc，min and P fc，max are the upper and lower limits of the fuel cell power respectively

[0158] (4) Battery

[0159]

[0160] SOC min ≤SOC≤SOC max (3-13)

[0161] Where:

[0162] Pxdc is the battery storage power; It is the lower limit of electrolytic cell operating power; It is the upper limit of electrolyzer operating power. min and SOC max The upper and lower limits of the battery state of charge.

[0163] 4. Multi-objective optimization

[0164] Based on the principle of PSO optimization algorithm, this section will optimize the configuration of the electric hydrogen coupling system, taking the electrolytic cell capacity, hydrogen storage tank capacity, and fuel cell capacity as system optimization variables, inputting meteorological information, constraints, and load data, and S The net profit function expressed is used as the fitness function, and the optimal solution is obtained by using an iterative algorithm. The process is as follows Figure 2 , as shown in the capacity optimization process.

[0165] The calculation steps of the multi-objective particle swarm optimization algorithm are:

[0166] ① Data entry: input data into the corresponding power generation system and electric-hydrogen coupling system;

[0167] ② Data initialization: Randomize the output of photovoltaic power generation, wind turbine generation, electrolytic cell generation, hydrogen storage tank generation, and fuel cell generation;

[0168] ③ Constrained energy supply configuration: The configuration in the initial data is linked and constrained according to the given constraints.

[0169] ④ Iterative optimization: Bring the configuration obtained in each generation into the net profit F S The cost function expressed is calculated by continuously updating the population to retain the maximum net profit F S Until the number of iterations reaches 100;

[0170] ⑤Output results.

[0171] 5. Data Normalization

[0172] Since the installed capacity of each device in the coupled system is different, normalization is required when analyzing the flexibility margin. The commonly used normalization method is to normalize the sample data to a value in the interval (0, 1), as shown in the formula.

[0173]

[0174] Where:

[0175] is the maximum and minimum value of the equipment flexibility margin; is the actual flexibility margin of the equipment at time i.

[0176] The purpose of the present invention is to provide a method for calculating the system flexibility margin based on electric-hydrogen coupling to solve the problem of insufficient flexibility and efficiency of energy systems in the prior art and to achieve safe, reliable, economical and efficient operation in energy systems. The method optimizes the system operation strategy by constructing a mathematical model of the electric-hydrogen coupling system and combining it with advanced optimization algorithms to improve system flexibility and overall efficiency. The features and advantages of the present invention are as follows:

[0177] (1) The flexibility margin calculation method of electric hydrogen multi-node is of great significance in the case of high renewable energy access. At present, there is a gap between the research on the flexibility margin of the electric hydrogen system and the actual system operation. The current research mainly focuses on power balance processing and lacks a specific analysis of system flexibility. The present invention is based on the electric hydrogen multi-node system and proposes a flexibility margin calculation method under the electric hydrogen multi-node.

[0178] (2) The present invention constructs a mathematical model of an electric-hydrogen multi-node system, including various energy conversion forms such as wind power generation, photovoltaic power generation, water electrolysis to produce hydrogen, hydrogen storage, and fuel cell power generation, involving energy types such as electricity and hydrogen, to achieve flexible conversion and regulation of the energy system.

[0179] (3) The present invention constructs a flexibility margin optimization model, defines a mathematical model of flexibility supply and demand, considers the characteristics of flexibility resources, comprehensively evaluates and optimizes flexibility resources from multiple angles and multiple levels, and improves the overall efficiency of the system. The model also emphasizes the balance and normalization of flexibility supply and demand, solves the problems of reduced system inertia and weakened anti-interference ability caused by the access of a high proportion of new energy, and provides a highly adaptable microgrid flexibility margin optimization scheduling method.

[0180] (4) The present invention further constructs a calculation model for the total cost, total revenue and net profit of the system over its entire life cycle, including the initial equipment investment cost, operation and maintenance cost, total operating cost, total economic benefit and net profit calculation model, to comprehensively evaluate the economic efficiency of the system.

[0181] (5) The present invention adopts a PSO-based multi-objective optimization algorithm to optimize the configuration of the electrolytic cell capacity, hydrogen storage tank capacity and fuel cell capacity. The goal is to minimize the overall operating cost of the microgrid, maximize the system net profit, achieve the optimal configuration of the electric-hydrogen coupling system, and improve the flexibility of the system and the overall operating efficiency.

[0182] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected, and the scope of the present invention to be protected is defined by the attached claims and their equivalents.

Claims

1. A method for calculating system flexibility margin based on electricity-hydrogen coupling, characterized in that: The method for calculating the system flexibility margin based on electricity-hydrogen coupling comprises the following steps: (1) Establish a mathematical model of the electric-hydrogen coupled multi-node system, including a water electrolysis hydrogen production module, a hydrogen storage module, and a fuel cell power generation module; (2) Establish a flexibility margin model for electricity-hydrogen coupling, including flexible power sources on the load side and flexible power sources on the source side; (3) Establish a total cost calculation model for the entire life cycle of the electric hydrogen system, including initial equipment investment cost, equipment operation and maintenance cost, total operating cost, total economic benefit, net profit calculation model and constraints; (4) Iteratively optimize the configuration of the electric hydrogen system based on the PSO algorithm to achieve the optimal solution; (5) Normalize the equipment in the system to achieve the universality of flexibility margin analysis under different equipment capacity conditions.

2. The method for calculating system flexibility margin based on electricity-hydrogen coupling according to claim 1 is characterized in that: In step (1), the energy supply equipment in the system includes various generator sets, renewable energy units, and hydrogen power generation equipment. The energy storage module in the system includes batteries and hydrogen storage tanks. The system energy users include users of different power nodes, electrolyzers, and battery equipment. The hydrogen fuel cell is an important source of electricity in the system, and the electrolyzer is the main source of hydrogen energy in the system. The important coupling element for realizing electric-hydrogen conversion uses hydrogen energy and its related energy equipment to realize the coupling of different energy forms, which can enhance the complementary coordination between different energy forms in the system and form a highly flexible multi-energy complementary system.

3. The method for calculating system flexibility margin based on electricity-hydrogen coupling according to claim 1 is characterized in that: Based on the electric-hydrogen multi-node system, a flexibility margin calculation method under electric-hydrogen multi-node is proposed.

4. The method for calculating system flexibility margin based on electricity-hydrogen coupling according to claim 1 is characterized in that: A mathematical model of the electric-hydrogen multi-node system was constructed, including various energy conversion forms such as wind power generation, photovoltaic power generation, water electrolysis to produce hydrogen, hydrogen storage, and fuel cell power generation, involving energy types such as electricity and hydrogen, to achieve flexible conversion and regulation of the energy system.

5. The method for calculating system flexibility margin based on electricity-hydrogen coupling according to claim 1 is characterized in that: A flexible margin optimization model was constructed, and a mathematical model of flexibility supply and demand was defined. Taking into account the characteristics of flexibility resources, flexibility resources were comprehensively evaluated and optimized from multiple angles and levels to improve the overall efficiency of the system.

6. The method for calculating system flexibility margin based on electricity-hydrogen coupling according to claim 1 is characterized in that: A calculation model for the total cost, total revenue and net profit of the system's entire life cycle was constructed, including the initial equipment investment cost, operation and maintenance cost, total operating cost, total economic benefit and net profit calculation model, to comprehensively evaluate the system's economic feasibility.

7. The method for calculating system flexibility margin based on electricity-hydrogen coupling according to claim 1 is characterized in that: The PSO-based multi-objective optimization algorithm is used to optimize the configuration of the electrolytic cell capacity, hydrogen storage tank capacity and fuel cell capacity.

8. The method for calculating system flexibility margin based on electricity-hydrogen coupling according to claim 1 is characterized in that: Mathematical modeling of the electric-hydrogen coupled multi-node system includes: (1) Wind power generation system The wind turbine output is related to the wind speed, and its probability density expression for wind speed v is: Where: Γ is the gamma function; c is the amplitude coefficient; k is the scale coefficient; σ and μ are the standard deviation and sample mean of v respectively; The mathematical expression of the output of a single fan and the wind speed is: Where: v t is the actual wind speed; v in is the cut-in wind speed; v out is the cut-out wind speed; v r Refers to the rated wind speed; p wtr Refers to the rated output power; P wt (t) refers to the actual output power of the fan.

9. The method for calculating system flexibility margin based on electricity-hydrogen coupling according to claim 1 is characterized in that: The mathematical modeling of the electric-hydrogen coupled multi-node system also includes: Photovoltaic power generation system: In order to consider the actual situation and reduce the error, the actual output power of the photovoltaic cell is related to the solar radiation intensity and the ambient temperature, so its mathematical expression is: or loss (t)=1+λ(T(t)-25) (1-4) Where: C PV is the rated power of the photovoltaic cell; S (t) is the light intensity at time t; S ST is the standard light intensity; η pv_DC_DC is the photovoltaic power exchange efficiency; η loss is the power loss of the photovoltaic cell; λ is the temperature coefficient, which can be taken as; T(t) is the operating temperature of the equipment; T a (t) is the actual ambient temperature; T N The standard temperature.

10. The method for calculating system flexibility margin based on electricity-hydrogen coupling according to claim 1, characterized in that: The mathematical modeling of the electric-hydrogen coupled multi-node system also includes: Electric-hydrogen coupled system: When the wind and solar output power is greater than the power demand in the park, the electrolyzer starts working to convert the surplus electricity into hydrogen energy, and stores the excess hydrogen in the hydrogen storage tank; when the wind and solar resources are not enough to supply the demand, the hydrogen stored in the hydrogen storage tank will be used as fuel cell fuel for power generation.

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