A method for optimizing configuration of wind power hydrogen production and energy storage system considering hydrogen blending ratio constraint

Abstract

This invention proposes a method for optimizing the capacity configuration of a wind power-hydrogen-HCNG energy system considering hydrogen blending ratio constraints. The method includes establishing physical models of the electrolyzers, hydrogen storage tanks, and fuel cells within the wind power-hydrogen-HCNG system; establishing a mixed integer programming model based on wind power output, electrical load, and natural gas load, with the goal of maximizing system revenue, considering power, hydrogen balance, and various equipment constraints, to initially calculate the initial capacity of the electrolyzer array; obtaining the range of electrolyzer number configurations based on the electrolyzer overload characteristics and initial capacity; proposing a two-layer rotation strategy for multi-electrolyzer combined operation considering overload operation; and solving the mixed integer programming model by sequentially substituting the number of electrolyzers based on this strategy to obtain the optimal capacity configuration and hydrogen blending ratio. Compared with existing technologies, this invention effectively reduces system investment and operating costs, extends electrolyzer lifespan, and enables long-distance hydrogen transportation while simultaneously mitigating wind curtailment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wind power hydrogen production, and particularly relates to a wind power hydrogen production energy storage system capacity optimization configuration method considering hydrogen mixing ratio constraints. BACKGROUND

[0002] Renewable energy such as wind power and photovoltaic will gradually replace traditional fossil energy to dominate the energy field. In view of the current new energy consumption problem, large-scale wind-solar hydrogen production has become a current research hotspot. However, in wind-solar abundant areas, there is generally no large-scale hydrogen demand, and the establishment of a dedicated hydrogen pipeline requires time and capital cost, and the development of hydrogen mixed natural gas technology (HCNG) provides a new way for hydrogen transportation. Many domestic and foreign studies have confirmed the feasibility of hydrogen mixing in natural gas pipelines. Through the discussion on the current situation of global natural gas hydrogen mixing research, typical project cases, technical problems and application advantages, it is considered that hydrogen mixing into the existing natural gas pipeline facilities is one of the effective solutions to reduce the cost of hydrogen transportation in the early stage of hydrogen energy development. The wind power hydrogen production system considering hydrogen mixing in natural gas pipelines has become a hotspot in the research of renewable energy hydrogen production.

[0003] In the wind power hydrogen production energy storage system, the HCNG technology needs to consider the hydrogen mixing ratio constraints and the characteristics of the hydrogen production equipment, select appropriate capacity and power, and optimize the system configuration to ensure the economic and stable operation of the system. At present, scholars at home and abroad focus on the modeling of the balance of each node in the electric-gas network when hydrogen is mixed, and the hydrogen production equipment is regarded as a whole, without paying attention to the operating characteristics of the hydrogen production equipment. Since the capacity of a single electrolytic cell is small, large-scale water electrolysis hydrogen production systems are composed of multiple electrolytic cells operating in combination. Therefore, it is necessary to study the control strategy for the combined operation of multiple electrolytic cells based on the operating characteristics of the electrolytic cells.

[0004] The key equipment of the hydrogen production technology is the electrolytic cell. At present, alkaline electrolytic cells have been fully industrialized and are the best choice for large-scale production of green hydrogen. However, there is little research on the coordinated operation of multiple electrolytic cells. When the traditional control strategy for multiple electrolytic cells is adopted, the use time of the electrolytic cells will deviate too much, the overall service life of the electrolytic cells will be shortened, and even the electrolytic cells will be in a low-power operating condition, causing dangerous accidents. SUMMARY

[0005] The purpose of the present application is to combine the HCNG technology in the existing wind power hydrogen production system to solve the problem of hydrogen transportation, and to propose a wind power hydrogen production energy storage system capacity optimization configuration method considering hydrogen mixing ratio constraints to solve the problem of uneven service life of electrolytic cells in large-capacity hydrogen production systems.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A wind power hydrogen production energy storage system capacity optimization configuration method considering hydrogen mixing ratio constraint, the method comprising the following steps:

[0008] (1) Establishing a physical model of electrolytic cell, hydrogen storage tank and fuel cell in the wind power hydrogen production energy storage system;

[0009] (2) According to wind power output, electric load and natural gas load, taking the maximum system benefit as the target, considering power, hydrogen balance and various device constraints, establishing a mixed integer programming model, taking the electrolytic cell as a whole, preliminarily calculating the initial capacity of electrolytic cell array;

[0010] (3) Based on the overload characteristics and initial capacity of electrolytic cell, obtaining the electrolytic cell number configuration interval;

[0011] (4) Considering the overload operation of electrolytic cell, proposing a double-layer shift strategy of multi-electrolytic cell combined operation;

[0012] (5) Based on the double-layer shift strategy of multi-electrolytic cell combined operation, bringing the electrolytic cell number into the model for solution in sequence, selecting the capacity configuration and hydrogen mixing ratio making the system economic optimal.

[0013] Further, step (1) is specifically: the wind power-hydrogen energy-HCNG system comprises: electrolytic cell, hydrogen storage tank, fuel cell, HCNG system, and the operation models of various devices are established as follows:

[0014] In the HCNG system, the input natural gas load is Hydrogen mixing ratio The hydrogen mixing rate is calculated by the following formula

[0015]

[0016] The equivalent state of charge SOH of the hydrogen storage tank is calculated by the following formula:

[0017]

[0018] Wherein: is the hydrogen storage tank charging and discharging rate; S c is the configured hydrogen storage tank capacity; t represents the time, with the time scale of hours;

[0019] The fuel cell input-output model is calculated by the following formula:

[0020]

[0021] Wherein: is the fuel cell output power, MW; is the hydrogen consumption of the fuel cell, m 3 ; η fcFor fuel cell efficiency, take 45%; μ is the hydrogen consumption of fuel cell production per unit of electricity;

[0022] According to the electrolyzer input power P el , electrolyzer rated power P n , the electrolyzer hydrogen production rate is calculated by the following formula:

[0023]

[0024] The electrolyzer overload rate is set to λ n , calculated by the following formula:

[0025]

[0026] Where: The length of the overload operation and the total operation of electrolyzer n respectively.

[0027] Further, the step (2) is specifically to obtain the initial capacity of electrolyzer by the following mixed integer linear programming model:

[0028] First, the power of electrolyzer, hydrogen storage tank, capacity of fuel cell and hydrogen blending ratio are taken as decision variables;

[0029] Then, the objective function is established to maximize system revenue:

[0030] max C=C4-(C1+C2+C3)

[0031]

[0032] Where: C is the annual revenue; C4 is the hydrogen sales revenue; C1 is the investment cost; C2 is the maintenance cost; C3 is the gas purchase cost, ten thousand yuan; c i,inv is the equipment type capacity, MW, including electrolyzer, hydrogen storage tank, fuel cell; c i is the unit capacity cost corresponding to the equipment, MW / ten thousand yuan; r is the discount rate, take 0.1; Y is the system operation cycle, take 20 years; λ is the maintenance cost coefficient, take 0.02; T take 24 hours; c HG is the hydrogen blending transportation unit price, m 3 / yuan; is the hydrogen price, m 3 / yuan;

[0033] Finally, the power, hydrogen balance and equipment constraints in the system are established:

[0034] The power constraint is as follows:

[0035]

[0036] Where: These are wind power and fuel cell power, respectively, in MW; For electrical load, MW; The input power to the electrolyzer array is denoted by x; a value of 1 indicates that the system experiences wind curtailment, and the electrolyzer array starts up; a value of 1 indicates that the system has a load deficit, and the fuel cell starts up.

[0037] Hydrogen confinement is given by the following formula:

[0038]

[0039] in: v el，n , These represent the hydrogen production rate of the electrolyzer array and a single electrolyzer, the hydrogen storage tank charging and discharging rate, the hydrogen blending rate in the natural gas pipeline, and the hydrogen consumption rate of the fuel cell, respectively. 3 / h; n is the electrolytic cell number, N is the total number of electrolytic cells;

[0040] The constraints of the hydrogen storage tank are as follows:

[0041]

[0042] Wherein: SOH min SOH max m represents the upper and lower limits of the equivalent state of charge of the hydrogen storage tank. 3 a and b are binary variables. When a is 1, it means that the hydrogen production of the electrolyzer is sufficient and the hydrogen storage tank starts storing hydrogen. When b is 1, it means that the hydrogen production of the electrolyzer is insufficient and the hydrogen storage tank supplies hydrogen to the natural gas pipeline. These represent the rates of hydrogen input and output from the hydrogen storage tank, respectively; SOH 0 SOH T These represent the equivalent state of charge of the hydrogen storage tank at the beginning and end of the time interval, respectively.

[0043] The constraints for fuel cells are as follows:

[0044]

[0045] in: The configuration capacity of the fuel cell is expressed in MW.

[0046] The hydrogen doping ratio constraint is given by the following formula:

[0047]

[0048] The overload duration constraint for the electrolytic cell is as follows:

[0049] 0≤λ n ≤0.5.

[0050] Further, step (3) specifically involves determining the range of electrolytic cell configurations using the following formula:

[0051]

[0052] Where: P' EL The initial capacity of the electrolytic cell array is MW; The capacity allowed for full overload of the electrolytic cell, MW; The function is the floor function; N1 is the initial number of units configured; N2 is the number of units configured after considering overload characteristics; α is the overload coefficient; P n This is the rated power of the electrolytic cell.

[0053] Furthermore, step (4) specifically includes:

[0054] Step (41): Based on the input power of the electrolytic cell array and the overload characteristics of the electrolytic cell, determine the number and power of the electrolytic cells at time t that are rated, overloaded, fluctuating, or shut down.

[0055] Step (42): Use a two-layer rotation strategy to determine the operation number of the electrolytic cell.

[0056] Furthermore, the specific method of step (41) is as follows:

[0057] Step (411): Based on the input power of a single electrolytic cell, the electrolytic cells are divided into four operating states: P el =0 indicates a shutdown state; P el =P n Rated operating condition; P el =120%P n Overload operating condition; 20% P n ≤P el ≤P n P n ≤P el ≤120%P n It is in a fluctuating state;

[0058] Step (412): Based on the number of input electrolytic cells N, N∈[N2,N1], the input power P of the electrolytic cell array is... EL L represents the theoretically recommended number of electrolytic cells operating at rated capacity, and P represents... b The overload power is calculated using the following formula:

[0059]

[0060]

[0061] in: This is the floor function.

[0062] If L≤N, proceed to step (413); otherwise, proceed to step (414).

[0063] Step (413): Based on the input power P of the electrolytic cell array EL Overload power P b Determine the number of electrolytic cells currently operating under overload (M1), rated operation (L'1), fluctuating operation (X1), and shutdown (I1), satisfying M1 + L'1 + X1 + I1 = N.

[0064] Step (414): Based on the input power P of the electrolytic cell array EL Overload power P b Determine the number of electrolytic cells currently operating under overload (M2), rated operation (L'2), fluctuating operation (X2), and shutdown (I2), satisfying M2 + L'2 + X2 + I2 = N.

[0065] Furthermore, the specific method of step (413) is as follows:

[0066] If P b ≤20%P n If the remaining power is insufficient to ensure the safe operation of the next electrolytic cell, the already started electrolytic cells will be placed in a high-power operating condition. At this time, M1=0, L'1=L-1, X1=1, I1=N-X1-L'1. The power of the electrolytic cells in each state will be determined according to the following formula:

[0067]

[0068] If 20% P n ≤P b ≤P n If the remaining power is sufficient to ensure the safe operation of the next electrolytic cell, then the next electrolytic cell is started. At this time, M1 = 0, L'1 = L, X1 = 1, I1 = N - X1 - L'1. Simultaneously, the power of the electrolytic cell in each state is determined according to the following formula:

[0069]

[0070] Furthermore, the specific method of step (414) is as follows:

[0071] First, all N electrolytic cells are put into rated operation. Then, the overload power is distributed sequentially to the electrolytic cells operating at rated power, resulting in M2 electrolytic cells being overloaded. Finally, the remaining power P is... s Assigned to an electrolytic cell operating at its rated power, M2, P s The calculation formula is as follows:

[0072]

[0073] At this point, L'2 = N - M2 - 1, X2 = 1, I2 = 0, and the power of the electrolytic cell in each state is determined according to the following formula:

[0074]

[0075] Further, step (42) is specifically implemented as follows: each electrolytic cell is numbered sequentially from smallest to largest. The electrolytic cell array adopts a two-layer rotation strategy. The outer layer follows the principle of first-to-start and first-to-shutdown, starting the electrolytic cells sequentially from smallest to largest according to the determined rated, overload, fluctuation, and shutdown power and number of cells. At the next moment, when the input power increases, the electrolytic cell with the larger number is started first; when the input power decreases, the electrolytic cell with the smaller number is shut down first, and so on. The inner layer adopts a rotation strategy, rotating the electrolytic cells in overload and fluctuation states sequentially from smallest to largest among the started electrolytic cells, ensuring as much as possible that the electrolytic cells in overload and fluctuation states at time t are operating at rated speed at the next moment.

[0076] Further, step (5) specifically involves: based on the modeling of the electrolyzer configuration range, operating strategy and optimization model, substituting N into the mixed integer linear programming model in sequence to solve the problem, and selecting the configuration capacity and hydrogen doping ratio that make the system economically optimal.

[0077] The present invention also provides a capacity optimization configuration system for a wind power hydrogen production and storage system considering hydrogen doping ratio constraints. The system includes a memory and a processor. The memory is used to store a computer program, and the processor is used to implement the above-mentioned capacity optimization configuration method for a wind power hydrogen production and storage system considering hydrogen doping ratio constraints when the computer program is executed.

[0078] Compared with the prior art, the present invention has the following advantages:

[0079] This invention combines HCNG technology with a wind power hydrogen production system, transporting hydrogen through natural gas pipelines, effectively reducing system operating costs. In the capacity configuration model, the overload characteristics of electrolyzers are utilized to reduce the capacity configuration requirements of electrolyzers, thereby reducing investment costs. Simultaneously, considering electrolyzers under overload operation, a two-layer rotation strategy for multi-electrolyzer combined operation is proposed based on the operating characteristics of electrolyzers, effectively balancing the operating time of each electrolyzer and preventing the operating power of electrolyzers from falling below the safe operating power. Attached Figure Description

[0080] Figure 1 This is a schematic diagram of the system structure of a wind power hydrogen production and storage system capacity optimization configuration method considering hydrogen doping ratio constraints according to the present invention.

[0081] Figure 2a , Figure 2b This invention relates to the hourly wind power output, electrical load, and natural gas pipeline flow rate of a certain region in an embodiment of the invention; wherein, Figure 2aFor wind power output and electrical load curves, Figure 2b This is a flow rate curve for a natural gas pipeline.

[0082] Figure 3 The output curves for days with scarce and abundant wind power are shown in the embodiments of the present invention.

[0083] Figure 4a , Figure 4b These are the electrolyzer operating power curves under two strategies on a typical day in this invention embodiment; wherein, Figure 4a The power curve of the electrolyzer under the traditional start-stop strategy is shown. Figure 4b The electrolyzer operating power curve under the two-layer rotation strategy;

[0084] Figure 5a , Figure 5b The figures show the electrolytic cell operating power curves under two strategies during days of wind power scarcity in this embodiment of the invention; wherein, Figure 5a The power curve of the electrolyzer under the traditional start-stop strategy is shown. Figure 5b The electrolyzer operating power curve under the two-layer rotation strategy;

[0085] Figure 6a , Figure 6b The figures show the electrolytic cell operating power curves under two strategies on days with sufficient wind power, as described in this embodiment of the invention. Figure 6a The power curve of the electrolyzer under the traditional start-stop strategy is shown. Figure 6b The electrolyzer operating power curve under the two-layer rotation strategy;

[0086] Figure 7 This is a schematic diagram illustrating the standard deviation of electrolytic cell operating time under three wind power scenarios in this embodiment of the invention;

[0087] Figure 8 This is a schematic diagram illustrating the system revenue under different distances and transportation methods in an embodiment of the present invention. Detailed Implementation

[0088] The present invention will now be clearly and completely described with reference to the accompanying drawings and specific examples. Note that the described embodiments are only some, not all, of the embodiments of the present invention, and the present invention is not intended to limit its use or purpose.

[0089] The present invention provides a method for optimizing the capacity configuration of a wind power-to-hydrogen storage system considering hydrogen doping ratio constraints. The method includes the following steps:

[0090] Step (1): Establish the physical models of the electrolyzer, hydrogen storage tank, fuel cell, and HCNG system in the wind power-hydrogen-HCNG system as follows:

[0091] The HCNG system is based on the input natural gas load. Hydrogen doping ratio The hydrogen doping rate is calculated using the following formula.

[0092]

[0093] The equivalent state of charge of a hydrogen storage tank is calculated by the following formula:

[0094]

[0095] in: The charging and discharging rate of the hydrogen storage tank; S c The capacity of the configured hydrogen storage tank; t represents time, measured in hours;

[0096] The fuel cell input-output model is calculated by the following formula:

[0097]

[0098] in: The output power of the fuel cell is expressed in MW. m is the amount of hydrogen consumed by the fuel cell. 3 η fc denoted as 45% for fuel cell efficiency; μ represents the amount of hydrogen consumed per unit of electricity produced by the fuel cell.

[0099] Set the rated power P of the electrolytic cell n The value is 2MW, based on the input power P. el The linearized expression for the hydrogen production rate of the electrolyzer is obtained from the following formula:

[0100]

[0101] The overload rate of the electrolytic cell is set to λ. n

[0102]

[0103] in: These are the overload running time and total running time of electrolytic cell n, respectively.

[0104] Step (2): Based on wind power output, electrical load, and natural gas load, with the goal of maximizing system revenue, and considering power, hydrogen balance, and various equipment constraints, a mixed integer programming model is established. The electrolyzer is treated as a whole, and the initial capacity of the electrolyzer array is initially calculated; specifically:

[0105] The initial capacity of the electrolyzer is obtained using the following mixed-integer linear programming model:

[0106] First, the power of the electrolyzer, the hydrogen storage tank, the capacity of the fuel cell, and the hydrogen blending ratio are used as decision variables;

[0107] Then, establish the objective function to maximize system benefits:

[0108]

[0109] Where: C represents annual revenue; C4 represents hydrogen sales revenue; C1 represents investment cost; C2 represents maintenance cost; C3 represents gas purchase cost (in ten thousand yuan); c i,inv The capacity of the equipment is expressed in MW, including electrolyzers, hydrogen storage tanks, and fuel cells; c i The unit capacity cost of the equipment is MW / 10,000 yuan; r is the discount rate, taken as 0.1; Y is the system operating cycle, taken as 20 years; λ is the maintenance cost coefficient, taken as 0.02; T is taken as 24 hours; c HG The unit price for hydrogen-blended transportation, m 3 / yuan; c H2 m is the unit price of hydrogen. 3 / Yuan;

[0110] Finally, establish the power, hydrogen balance, and equipment constraints in the system:

[0111] Power constraints:

[0112]

[0113] in: These are wind power and fuel cell power, respectively, in MW; For electrical load, MW; The input power to the electrolyzer array is denoted by x; a value of 1 indicates that the system experiences wind curtailment, and the electrolyzer array starts up; a value of 1 indicates that the system has a load deficit, and the fuel cell starts up.

[0114] Hydrogen confinement is given by the following formula:

[0115]

[0116] in: v el，n , These represent the hydrogen production rate of the electrolyzer array and a single electrolyzer, the hydrogen storage tank charging and discharging rate, the hydrogen blending rate in the natural gas pipeline, and the hydrogen consumption rate of the fuel cell, respectively. 3 / h; n is the electrolytic cell number, N is the total number of electrolytic cells;

[0117] The constraints of the hydrogen storage tank are as follows:

[0118]

[0119] Wherein: SOH min SOH max m represents the upper and lower limits of the equivalent state of charge of the hydrogen storage tank. 3a and b are binary variables. When a is 1, it means that the hydrogen production of the electrolyzer is sufficient and the hydrogen storage tank starts storing hydrogen. When b is 1, it means that the hydrogen production of the electrolyzer is insufficient and the hydrogen storage tank supplies hydrogen to the natural gas pipeline. These represent the rates of hydrogen input and output from the hydrogen storage tank, respectively; SOH 0 SOH T These represent the equivalent state of charge of the hydrogen storage tank at the beginning and end of the time interval, respectively.

[0120] The constraints for fuel cells are as follows:

[0121]

[0122] in: The configuration capacity of the fuel cell is expressed in MW.

[0123] The hydrogen doping ratio constraint is given by the following formula:

[0124]

[0125] The overload duration constraint for the electrolytic cell is as follows:

[0126] 0≤λ n ≤0.5.

[0127] Step (3): Based on the overload characteristics and initial capacity of the electrolytic cells, obtain the range of electrolytic cell configuration numbers; specifically:

[0128] The range of electrolytic cell configurations is determined by the following formula:

[0129]

[0130] Where: P' EL The initial capacity of the electrolytic cell array is MW; The capacity allowed for full overload of the electrolytic cell, MW; The function is the floor function; N1 is the initial number of units configured; N2 is the number of units configured after considering overload characteristics; a is the overload coefficient; P n This is the rated power of the electrolytic cell.

[0131] Step (4): Considering the overload operation of the electrolytic cells, a two-layer rotation strategy for coordinated operation of multiple electrolytic cells is proposed; specifically including:

[0132] Step (41): Based on the input power of the electrolytic cell array, determine the number and power of the electrolytic cells at time t that are rated, overloaded, fluctuating, or shut down. Specifically, this includes:

[0133] Step (411): Based on the input power of a single electrolytic cell, the electrolytic cells are divided into four operating states: P el =0 indicates a shutdown state; P el =Pn Rated operating condition; P el =120%P n Overload operating condition; 20% P n ≤P el ≤P n P n ≤P el ≤120%P n It is in a fluctuating state;

[0134] Step (412): Based on the number of input electrolytic cells N, N∈[N2,N1], the input power P of the electrolytic cell array is... EL L represents the theoretically recommended number of electrolytic cells operating at rated capacity, and P represents... b The overload power is calculated using the following formula:

[0135]

[0136]

[0137] in, This is the floor function.

[0138] If L≤N, proceed to step (413); otherwise, proceed to step (414).

[0139] Step (413): Based on the input power P of the electrolytic cell array EL Overload power P b Determine the number of electrolytic cells currently operating under overload (M1), rated operation (L'1), fluctuating operation (X1), and shutdown (I1), satisfying M1 + L'1 + X1 + I1 = N.

[0140] Specifically, if P b ≤20%P n If the remaining power is insufficient to ensure the safe operation of the next electrolytic cell, the already started electrolytic cells will be placed in a high-power operating condition. At this time, M1=0, L'1=L-1, X1=1, I1=N-X1-L'1. The power of the electrolytic cells in each state will be determined according to the following formula:

[0141]

[0142] If 20% P n ≤P b ≤P n If the remaining power is sufficient to ensure the safe operation of the next electrolytic cell, then the next electrolytic cell is started. At this time, M1=0, L'1=L, X1=1, I1=N-X1-L'1. Simultaneously, the power of the electrolytic cell in each state is determined according to the following formula:

[0143]

[0144] Step (414): Based on the input power P of the electrolytic cell array EL Overload power P b Determine the number of electrolytic cells currently operating under overload (M2), rated operation (L'2), fluctuating operation (X2), and shutdown (I2), satisfying M2 + L'2 + X2 + I2 = N.

[0145] Specifically, first, all N electrolytic cells are put into rated operation; then, the overload power is distributed sequentially to the electrolytic cells operating at rated power, resulting in M2 electrolytic cells being overloaded; finally, the remaining power P is... s Assigned to an electrolytic cell operating at its rated power, M2, P s The calculation formula is as follows:

[0146]

[0147] At this point, L'2 = N - M2 - 1, X2 = 1, I2 = 0, and the power of the electrolytic cell in each state is determined according to the following formula:

[0148]

[0149] Step (42): Use a two-layer rotation strategy to determine the operation number of the electrolytic cell.

[0150] Each electrolytic cell is numbered sequentially from smallest to largest. The electrolytic cell array employs a two-layer rotation strategy. The outer layer follows a first-start-first-shutdown principle, starting the electrolytic cells sequentially from smallest to largest number based on the determined rated, overload, fluctuation, and shutdown power levels. In the next time step, when the input power increases, the electrolytic cells with larger numbers start first; when the input power decreases, the electrolytic cells with smaller numbers shut down first, and so on. The inner layer uses a rotation strategy, taking turns starting the overloaded and fluctuating electrolytic cells from smallest to largest among the starting electrolytic cells, ensuring that electrolytic cells in overloaded or fluctuating states at time t are operating at rated power in the next time step.

[0151] Step (5): Based on the modeling of the electrolyzer configuration range, operation strategy and optimization model, N is successively substituted into the mixed integer linear programming model for solution, and the configuration capacity and hydrogen doping ratio that make the system economically optimal are selected.

[0152] Figure 2a , Figure 2b This embodiment represents the wind power output and electrical load of a large-scale wind farm in a certain region, the typical daily gas transmission volume of a natural gas pipeline, and the pipeline length of 300 km. Based on the capacity configuration model established in step (2), the initial capacity configuration scheme P' for the electrolyzer array is obtained. EL =18.52, take α as 1.2, the rated power of the electrolytic cell is 2MW;

[0153] Then, based on step (3), the configuration range for the number of electrolytic cells is obtained as [8, 10]:

[0154]

[0155] Substituting N sequentially into the mixed-integer linear programming model, we obtain the system configuration schemes and cost analyses in Tables 1 and 2:

[0156] Table 1. Configuration results for different numbers of electrolytic cells

[0157] Device N＝8 N＝9 N＝10 Electrolyzer / MW 16 18 20 Fuel cell / MW 6.5 6.5 6.5 Hydrogen storage tank / m 3 ]]> 43370 44931 65339 Hydrogen blending ratio 1.85％ 1.99％ 2％

[0158] Table 2. Economic Cost Analysis for Different Numbers of Electrolytic Cells

[0159] Type N＝8 N＝9 N＝10 Investment maintenance cost / 10,000 yuan 2327 2508 2642 Operating cost / 10,000 yuan 123 132 133 Hydrogen sales revenue / 10,000 yuan 2896 3113 3136 Profit / 10,000 yuan 445 473 361

[0160] As shown in Tables 1 and 2, when the number of electrolyzers is 8, the overload characteristics of the electrolyzers can meet the hydrogen blending requirements of the HCNG system. However, due to the efficiency characteristics of the electrolyzers, their operating efficiency gradually decreases with increasing input power, resulting in a reduction in the hydrogen production capacity of the overloaded section. Although the investment and maintenance costs are reduced by 1.81 million yuan compared to configuring 9 electrolyzers, the reduced hydrogen production leads to a decrease in hydrogen sales revenue of 2.17 million yuan. When the system is configured with 10 electrolyzers, the hydrogen blending ratio is not significantly different from that of 9 electrolyzers, meaning the hydrogen sales revenue is similar. However, the investment and maintenance costs of 10 electrolyzers are 1.34 million yuan higher than those of 9 electrolyzers. In conclusion, configuring 9 electrolyzers maximizes system revenue and provides the best economic benefits, with a hydrogen blending ratio of 1.99%.

[0161] To better analyze the two-level rotation optimization strategy, a comparison is made between the traditional start-stop strategy and the two-level rotation strategy.

[0162] The operating power of the electrolytic cell array is analyzed under three wind power scenarios. Figures 2 and 3 show the wind power output under the three scenarios.

[0163] Wind power is a typical example of the current situation, by Figure 4a It is known that when adopting the traditional start-stop strategy, the earlier the electrolyzer number, the longer its operating time. Electrolyzer No. 10 only operated for one hour a day at 0.5MW; electrolyzers No. 4, 5, and 9 all had periods where their operating power fell below the safe operating power. Over time, this uneven operating time will lead to a sharp decrease in the lifespan of the electrolyzer array. Figure 4bIt can be seen that when adopting a two-layer rotation strategy, the working time of each electrolytic cell is distributed as evenly as possible through the two-layer rotation. Electrolytic cell No. 9 is in a stopped state from 1 to 4 hours because the change in input power of the electrolytic cell at adjacent times is insufficient to restart an electrolytic cell. Considering the start-up and shutdown time of the electrolytic cells, electrolytic cells with smaller numbers are not shut down and electrolytic cell No. 9 is started instead. Only electrolytic cells in fluctuating or overloaded states are rotated among the operating electrolytic cells. That is, from 1 to 4 hours, the outer layer rotation stops, and the inner layer rotation is carried out in electrolytic cells No. 1 to 8.

[0164] Wind power is becoming increasingly scarce. Figure 5a As can be seen, when adopting the traditional start-stop strategy, due to the reduction in the amount of air curtailed, electrolyzers 3 to 10 remain shut down, with only electrolyzers 1 and 2 operating within 24 hours, resulting in a very harsh operating environment for the electrolyzers. As shown in Figure 5b, when adopting the dual-layer rotation strategy, electrolyzers 3 to 7 also operate for a portion of the time, but electrolyzers 8 and 9 remain shut down for the entire day.

[0165] On days with sufficient wind power, by Figure 6a It can be seen that when adopting the traditional start-stop strategy, electrolytic cells 1 to 8 always operate at their rated state, while electrolytic cells 9 and 10 always operate in a fluctuating state. This uneven power fluctuation between electrolytic cells also affects their overall lifespan, and electrolytic cell 10's power is lower than its safe operating power at times 4 and 13. Figure 6b It can be seen that when the two-layer rotation strategy is adopted, the power fluctuation trend of each electrolytic cell is relatively average, and the power of the electrolytic cells during operation is greater than the safe operating power.

[0166] To more clearly illustrate the effect of the dual-level rotation strategy, the standard deviation of the electrolyzer runtime under the two different strategies is calculated as follows: Figure 7 As shown in the figure, the standard deviation reflects the degree of deviation between the electrolyzer's operating time and the average operating time. The smaller the standard deviation, the more evenly the electrolyzer operates. The figure shows that, regardless of the scenario, the standard deviation using the traditional start-stop strategy is always larger than that using the dual-level rotation strategy. The difference is smallest when wind power is scarce, but largest when wind power is abundant. This indicates that the proposed strategy is more effective when wind power is plentiful. The dual-level rotation strategy can effectively average the electrolyzer's operating time while preventing the electrolyzer from operating under low-power conditions.

[0167] To illustrate the advantages of hydrogen-blended transportation, the benefits of cylinder truck and pipeline hydrogen-blended transportation systems are compared for different distances. In actual operation, the distance of hydrogen transportation affects the cost, and the system benefits differ when using cylinder trucks and pipelines for hydrogen-blended transportation at different distances. Figure 8As shown, when the transportation distance is 100km, the system revenue from using gas-powered trucks is 620,000 higher than that from pipelines with hydrogen blending. This is because gas-powered trucks deliver hydrogen as it is produced, eliminating the need for large-scale hydrogen storage tanks and resulting in lower capacity configuration costs. However, as the transportation distance increases, the unit cost of hydrogen transportation using gas-powered trucks is significantly higher than that using pipelines. When the transportation distance reaches 400km, the system can no longer generate revenue and incurs losses. In contrast, while the system revenue from pipelines with hydrogen blending decreases with increasing distance, the system remains profitable throughout. Therefore, using natural gas pipelines with hydrogen blending has a clear advantage in long-distance hydrogen transportation.

[0168] Therefore, the multi-electrolyte dual-layer rotation strategy based on the overload characteristics of electrolyzers can average the operating time of electrolyzers, avoid electrolyzers operating at low power, and extend the lifespan of the electrolyzer array. Utilizing the overload characteristics of electrolyzers, the capacity configuration of electrolyzers can be reduced. Considering the efficiency characteristics of electrolyzers, the capacity configuration model established in this paper can yield the configuration scheme and hydrogen blending ratio that optimizes the system's economy, providing a novel approach for wind curtailment and utilization. Through comparative analysis of hydrogen transportation distances, it is demonstrated that using hydrogen blending in natural gas pipelines has good economic efficiency and feasibility in long-distance hydrogen transportation.

[0169] The above embodiments are merely examples and are not intended to limit the scope of the invention. These embodiments can also be implemented in various other ways.

Claims

1. A method for optimizing the capacity configuration of a wind power-to-hydrogen storage system considering hydrogen doping ratio constraints, characterized in that, Includes the following steps: (1) Establish physical models of the electrolyzer, hydrogen storage tank, fuel cell, and HCNG system in the wind power-hydrogen-HCNG system; the wind power-hydrogen-HCNG system includes: electrolyzer, hydrogen storage tank, fuel cell, and HCNG system, and establish the operation models of each device as follows: The HCNG system is based on the input natural gas load. Hydrogen doping ratio The hydrogen doping rate can be calculated using the following formula. : ， Equivalent state of charge of hydrogen storage tank Calculated by the following formula: ， in: The charging and discharging rate of the hydrogen storage tank; The capacity of the configured hydrogen storage tank; t represents time, measured in hours; The fuel cell input-output model is calculated by the following formula: ， in: The output power of the fuel cell is expressed in MW. m is the amount of hydrogen consumed by the fuel cell. 3 ; For fuel cell efficiency, we take 45%. Hydrogen consumed per unit of electricity produced by fuel cells; According to the input power of the electrolytic cell rated power of electrolytic cell The hydrogen production rate of the electrolyzer can be calculated using the following formula: , The set electrolytic cell overload rate is Calculated by the following formula: ， in: , These are the overload operating time and total operating time of electrolytic cell n, respectively; (2) Based on wind power output, electrical load, and natural gas load, with the goal of maximizing system revenue, and considering power, hydrogen balance and various equipment constraints, a mixed integer programming model is established, and the electrolyzer is treated as a whole to preliminarily calculate the initial capacity of the electrolyzer array. (3) Based on the overload characteristics and initial capacity of the electrolytic cell, the range of the number of electrolytic cells is obtained; (4) Considering the overload operation of the electrolytic cells, a two-layer rotation strategy for the combined operation of multiple electrolytic cells is proposed, specifically as follows: Step (41): Based on the input power of the electrolytic cell array and the overload characteristics of the electrolytic cell, determine the number and power of the electrolytic cells at time t that are rated, overloaded, fluctuating, or shut down. Step (42): A two-layer rotation strategy is adopted to determine the operation number of the electrolytic cells, including: assigning each electrolytic cell a number in ascending order; the electrolytic cell array adopts a two-layer rotation strategy; the outer layer adopts the principle of first-to-start and first-to-shutdown, and starts the electrolytic cells in ascending order according to the determined rated, overload, fluctuation and shutdown power and number of cells; at the next moment, when the input power increases, the electrolytic cell with the larger number is started first, and when the input power decreases, the electrolytic cell with the smaller number is shut down first, and so on; the inner layer adopts a rotation strategy, and the electrolytic cells in the overload and fluctuation state are rotated in ascending order among the started electrolytic cells, so as to ensure that the electrolytic cells in the overload and fluctuation state at time t are in rated operation at the next moment. (5) Based on the dual-level rotation strategy of multi-electrolyte combination operation, the number of electrolyzers is sequentially substituted into the mixed integer programming model for solution, and the capacity configuration and hydrogen doping ratio that make the system economically optimal are selected.

2. The method for optimizing the capacity configuration of a wind power-to-hydrogen energy storage system considering hydrogen doping ratio constraints according to claim 1, characterized in that, Step (2) specifically involves obtaining the initial capacity of the electrolyzer using the following mixed-integer linear programming model: First, the power of the electrolyzer, the hydrogen storage tank, the capacity of the fuel cell, and the hydrogen blending ratio are used as decision variables; Then, establish the objective function to maximize system benefits: ， in: Annual income; Revenue from hydrogen sales; For investment costs; Maintenance costs; The cost of purchasing gas is 10,000 yuan. The capacity of equipment types is measured in MW, including electrolyzers, hydrogen storage tanks, and fuel cells. The unit capacity cost of the equipment is expressed in MW / ten thousand yuan. The discount rate is set to 0.

1. The system's operating cycle is set to 20 years. The maintenance cost coefficient is set to 0.02; Take 24 hours; The unit price for hydrogen-blended transportation. ; This refers to the unit price of hydrogen. ; Finally, establish the power and hydrogen balance in the system and the constraints of each device: The power balance constraint is as follows: ， in: , These are wind power and fuel cell power, respectively, in MW; For electrical load, MW; Input power to the electrolytic cell array; A value of 1 indicates that the system is experiencing wind curtailment, and the electrolyzer array is started. A value of 1 indicates a system load deficit, triggering the fuel cell to start. Input power to the electrolytic cell array; The hydrogen balance constraint is given by the following formula: ， in: , , , , These represent the hydrogen production rate of the electrolyzer array, the hydrogen production rate of a single electrolyzer, the hydrogen storage tank charging / discharging rate of the electrolyzer array, the hydrogen blending rate of the natural gas pipeline of the electrolyzer array, and the hydrogen consumption rate of the fuel cell of the electrolyzer array, respectively. 3 / h; n is the electrolytic cell number, N is the total number of electrolytic cells; The constraints of the hydrogen storage tank are as follows: ， in: , m represents the upper and lower limits of the equivalent state of charge of the hydrogen storage tank. 3 a, This is a binary variable. When a is 1, it means that the hydrogen production capacity of the electrolyzer is sufficient and the hydrogen storage tank starts storing hydrogen. A value of 1 indicates that the hydrogen production capacity of the electrolyzer is insufficient, and the hydrogen storage tank is supplying hydrogen to the natural gas pipeline. , These represent the rates of hydrogen input and output from the hydrogen storage tank, respectively. , These represent the equivalent state of charge of the hydrogen storage tank at the beginning and end of the time interval, respectively. The constraints for fuel cells are as follows: ， in: The configuration capacity of the fuel cell is expressed in MW. The hydrogen doping ratio constraint is given by the following formula: ， The overload rate constraints for electrolytic cells are as follows: 。 3. The method for optimizing the capacity configuration of a wind power-to-hydrogen energy storage system considering hydrogen doping ratio constraints according to claim 2, characterized in that, Step (3) specifically involves determining the range of electrolytic cell configurations using the following formula: ， in: The initial capacity of the electrolytic cell array is MW; The capacity allowed for full overload of the electrolytic cell, MW; It is a rounding function; The initial number of units configured; The number of units is configured to take overload characteristics into account; Overload factor; This is the rated power of the electrolytic cell.

4. The method for optimizing the capacity configuration of a wind power-to-hydrogen energy storage system considering hydrogen doping ratio constraints according to claim 3, characterized in that, The specific method of step (41) is as follows: Step (411): Based on the input power of a single electrolytic cell, the electrolytic cells are divided into four operating states: The machine is in a stopped state. It is in rated operating condition; This indicates an overload operating state. It is in a fluctuating state; Step (412): Based on the input number of electrolytic cells N, Electrolytic cell array input power ,set up This refers to the theoretically recommended number of electrolytic cells operating at their rated capacity. The overload power is calculated using the following formula: ， ， in: This is the floor function; like If the condition is met, proceed to step (413); otherwise, proceed to step (414). Step (413): Based on the input power of the electrolytic cell array Overload power Determine the number of electrolytic cells currently operating under overload conditions. The number of units in rated operation Number of fluctuations and the number of shutdown states ,satisfy ; Step (414): Based on the input power of the electrolytic cell array Overload power Determine the number of electrolytic cells currently operating under overload conditions. The number of units in rated operation Number of fluctuations and the number of shutdown states ,satisfy .

5. The method for optimizing the capacity configuration of a wind power hydrogen production and storage system considering hydrogen doping ratio constraints according to claim 4, characterized in that, The specific method of step (413) is as follows: like If the remaining power is insufficient to ensure the safe operation of the next electrolytic cell, the already started electrolytic cells will be placed in high-power operation mode. , , , Meanwhile, the power of the electrolytic cell in each state is determined according to the following formula: ， like If the remaining power is sufficient to ensure the safe operation of the next electrolytic cell, then the next electrolytic cell is started. , , , Meanwhile, the power of the electrolytic cell in each state is determined according to the following formula: 。 6. The method for optimizing the capacity configuration of a wind power hydrogen production and storage system considering hydrogen doping ratio constraints according to claim 5, characterized in that, The specific method of step (414) is as follows: First, all N electrolytic cells are put into rated operation; then, the overload power is sequentially distributed to the electrolytic cells operating at rated power. The TECH solvent cell was overloaded. Finally, the remaining power was used... It is assigned to an electrolytic cell operating at its rated power. , The calculation formula is as follows: ， at this time, , , Meanwhile, the power of the electrolytic cell in each state is determined according to the following formula: 。 7. The method for optimizing the capacity configuration of a wind power-to-hydrogen energy storage system considering hydrogen doping ratio constraints according to claim 1, characterized in that, The specific steps (5) are as follows: based on the configuration range of the electrolyzer, the operation strategy and the modeling of the optimization model, N is successively substituted into the mixed integer linear programming model for solution to obtain the optimal configuration capacity and hydrogen doping ratio of the system.

8. A capacity optimization configuration system for wind power hydrogen production and storage considering hydrogen doping ratio constraints, characterized in that, The system includes a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to implement, when executing the computer program, the capacity optimization configuration method for wind power hydrogen production and storage system considering hydrogen doping ratio constraints as described in any one of claims 1 to 7.

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