Power distribution network medium-and-long-term energy storage optimal configuration method considering energy bidirectional conversion

Abstract

The invention relates to the field of gas-electricity integrated comprehensive energy systems, in particular to a power distribution network medium-and-long-term energy storage optimal configuration method considering energy bidirectional conversion, which utilizes a proton exchange membrane electrolytic bath, an electrolytic hydrogen production device, a hydrogen storage device and a hydrogen fuel cell to realize bidirectional conversion of electric energy and hydrogen energy. The electrolytic cell produces and stores hydrogen when the power grid load is off-peak, and the hydrogen fuel cell generates and supplies power when the load is peak. According to the method, the capacity configuration model of the hydrogen energy storage system is established, the optimal economic cost is taken as a target, the construction cost and the operation and maintenance cost of the system are comprehensively considered, the utilization rate of renewable energy sources is improved to the maximum extent, wind and light abandoning phenomena are reduced, and the flexibility and the stability of a power distribution network are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of gas-electricity integrated comprehensive energy systems, and in particular to a method for optimizing the configuration of medium- and long-term energy storage in a distribution network taking into account bidirectional energy conversion. Background Art

[0002] Under the "dual carbon" goal, the energy structure transformation of the distribution network is imminent. Especially in the context of the increasing proportion of renewable energy power generation, the power system faces many challenges such as efficient absorption and stable operation. Although renewable energy such as wind power and solar energy are environmentally friendly, their volatility and randomness lead to instability in the operation of the distribution network. In order to cope with the volatility problems brought about by the access of new energy, existing technologies usually use battery energy storage or load adjustment methods to balance supply and demand. However, battery energy storage has problems such as high cost, limited storage time and energy loss, and cannot fully cope with large-scale and long-term energy storage needs. Therefore, the existing distribution network energy storage technology faces the problem of being unable to store energy on a large scale and efficiently, resulting in serious problems such as wind and solar power abandonment. Summary of the invention

[0003] In view of the many problems existing in the above-mentioned prior art, the present invention provides a method for optimizing the configuration of medium- and long-term energy storage in a distribution network that takes into account the bidirectional conversion of energy. The present invention uses a hydrogen energy storage system to achieve bidirectional conversion of electrical energy and hydrogen energy. When the load of the power grid is low, the proton exchange membrane electrolyzer converts electrical energy into hydrogen energy and stores hydrogen; when the load of the power grid is high, the hydrogen energy is converted into electrical energy and supplied to the power grid through a hydrogen fuel cell to ensure the stable power supply of the power grid. At the same time, the method of the present invention minimizes the construction and operation and maintenance costs through the optimization model, improves the utilization efficiency of energy, and reduces the waste of renewable energy.

[0004] A method for optimizing the configuration of medium- and long-term energy storage in a distribution network considering bidirectional conversion of energy comprises the following steps: Producing hydrogen by electrolysis using a proton exchange membrane electrolyzer, wherein the proton exchange membrane electrolyzer model is based on reversible voltage, electrode overvoltage and ohmic overvoltage to produce hydrogen using electrical energy; Modeling a hydrogen storage device, wherein the hydrogen storage device model sets a hydrogen storage balance constraint, an upper and lower limit constraint of the hydrogen storage capacity, and an input and output power constraint of the hydrogen storage tank; A hydrogen fuel cell model is constructed based on a proton exchange membrane fuel cell, wherein the proton exchange membrane fuel cell model converts hydrogen energy into electrical energy through an electrochemical reaction of hydrogen, and outputs electrical energy by taking into account operating temperature, conversion efficiency, and power regulation flexibility; Ensure that the active power output and input of each node in the distribution network are balanced. The power flow balance model comprehensively considers the power of local power generation, renewable energy access and bidirectional energy conversion; With the goal of optimizing economic costs, the capacity configuration of the energy storage system is optimized by combining the construction cost and annual operation and maintenance cost of the proton exchange membrane electrolyzer, hydrogen storage device and proton exchange membrane fuel cell.

[0005] Preferably, the voltage across the proton exchange membrane electrolyzer is calculated by the following formula:

[0006] in, is the voltage across a single electrolytic cell; is the reversible voltage; is the electrode overvoltage; is the ohmic overvoltage.

[0007] Preferably, the reversible voltage of the proton exchange membrane electrolyzer is calculated by the following formula:

[0008] in, is the operating temperature of the proton exchange membrane electrolyzer, which ranges from 60 to 80 degrees Celsius; is the ideal gas constant, take 8.314 ; is the Faraday constant, take 96485 ; represents the hydrogen partial pressure at the cathode of the electrolyzer, which is 6.9 ; represents the oxygen partial pressure at the anode of the electrolytic cell, taking 1.3 .

[0009] Preferably, the hydrogen storage balance constraint of the hydrogen storage device model is calculated by the following formula:

[0010] in, is the hydrogen storage capacity of the hydrogen storage tank at time t; and They are the input and output hydrogen power of the hydrogen storage tank at time t respectively; and They are the storage and release efficiency of the hydrogen storage tank respectively.

[0011] Preferably, the electrical energy output power of the proton exchange membrane fuel cell model is calculated by the following formula:

[0012] In the formula, is the open circuit voltage of the proton exchange membrane fuel cell; is the activation loss voltage, which is related to the activation loss at low current density and is used to drive the electrochemical reaction; It is the ohmic loss voltage of the proton exchange membrane fuel cell, which is related to the voltage loss on the contact resistance, etc. It is the concentration loss voltage, which is related to the uneven concentration produced when the reactants are consumed rapidly.

[0013] Preferably, the energy conversion efficiency of the proton exchange membrane fuel cell is calculated by the following formula:

[0014] in, is the rate at which the proton exchange membrane fuel cell consumes hydrogen; Indicates that there is The total electrical power generated by the proton exchange membrane fuel cells operating in series is: It is the total power generated by the chemical reaction of the proton exchange membrane fuel cell.

[0015] Preferably, the economic cost objective function of the optimization configuration model is calculated by the following formula:

[0016] in, , , and They are comprehensive equivalent annual cost, investment cost, maintenance cost and operating cost; It is the operating cost of hydrogen energy storage.

[0017] Preferably, the economic cost objective function also includes penalty costs for abandonment of renewable energy sources such as wind and solar power.

[0018] Compared with the prior art, the advantages and beneficial effects of the present invention are: The present invention realizes the two-way conversion of electric energy and hydrogen energy by introducing a hydrogen energy storage system, utilizes surplus electricity to produce hydrogen when the grid load is low, and generates electricity through hydrogen fuel cells when the load is peak, thus solving the problems of small scale, high cost and large energy loss of battery energy storage in the prior art.

[0019] The present invention realizes long-term and efficient storage of energy through the technical means of proton exchange membrane electrolyzer, electrolytic hydrogen production, hydrogen storage device and hydrogen fuel cell, and reduces the construction and operation and maintenance costs to a minimum through optimization model, further reduces the wind and solar power abandonment rate, and improves the utilization rate of new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 The electrolytic cell working flow diagram of the present invention; Figure 3 This is a flow chart of the hydrogen storage device model in the present invention; Figure 4 It is a schematic diagram of the hydrogen fuel cell power generation process in the present invention. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is obvious that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0022] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0023] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0024] like Figure 1 As shown, the present invention provides a method for optimizing the configuration of medium- and long-term energy storage in a distribution network taking into account bidirectional conversion of energy, with respect to an integrated energy system.

[0025] The present invention is used to establish a hydrogen energy storage system consisting of an electrolyzer for hydrogen production by electrolysis, a hydrogen storage device, and a hydrogen fuel cell as medium- and long-term energy storage for the distribution network. The system can realize two-way conversion of electric energy and hydrogen energy, use excess electric energy to produce hydrogen when the grid load is low, and store the hydrogen. When the grid load is peak, hydrogen is used to generate electricity to improve the power supply capacity of the grid. On this basis, a method for optimizing the configuration of medium- and long-term energy storage for the distribution network is established, with the economic cost of the construction and operation and maintenance of the distribution network as the objective function. The specific steps are as follows: like Figure 2 As shown, step 1: establish an electrolyzer model that can realize the electrolytic hydrogen production process, where the electrolyzer selects a proton exchange membrane electrolysis device with high efficiency, medium cost, fast response speed and good flexibility. The model is as follows: When a current is applied between the cathode and the anode, the reaction that occurs at the anode is:

[0026] The anode reaction produces hydrogen ions, which then pass through the proton exchange membrane and participate in the reaction at the cathode of the electrolyzer.

[0027] The reaction equation at the cathode of the electrolytic cell is:

[0028] The overall chemical reaction formula of proton exchange membrane electrolysis is:

[0029] The proton exchange membrane electrolyzer electrolyzes water to produce oxygen at the anode and hydrogen at the cathode.

[0030] The electrolysis equipment of the present invention is used to absorb the excess power when the grid load is low, and requires multiple proton exchange membrane electrolyzers to operate in series. The voltage across a single proton exchange membrane electrolyzer is: (1) in, is the voltage across a single electrolytic cell. The electrolysis reaction in proton exchange membrane electrolysis is not spontaneous. is the minimum starting voltage of the reaction (i.e., reversible voltage), is the electrode overvoltage, is the ohmic overvoltage. The concentration overvoltage is ignored in this model because in the proton exchange membrane electrolyzer, the concentration overvoltage is much smaller than and sum.

[0031] The calculation formula for the reversible voltage of the proton exchange membrane electrolyzer is: (2) In the formula, It is the operating temperature of the proton exchange membrane electrolyzer, which is generally between 60 and 80 degrees Celsius; is the ideal gas constant, take 8.314 ; is the Faraday constant, take 96485 ; represents the hydrogen partial pressure at the cathode of the electrolyzer, which is 6.9 ; represents the oxygen partial pressure at the anode of the electrolytic cell, taking 1.3 .

[0032] The calculation formula for electrode overvoltage is: (3) In the formula, is the anode current density, ; is the cathode current density, ; It is the current density of the proton exchange membrane electrolyzer, which is the ratio of the current flowing through the proton exchange membrane electrolyzer to the effective area of ​​the electrolyzer.

[0033] (4) in, is the current flowing through the proton exchange membrane electrolyzer, is the effective area of ​​a single electrolytic cell, taken as 212.5 .

[0034] The ohmic overvoltage calculation formula for proton exchange membrane electrolyzer is: (5) In the formula, is the thickness of the proton exchange membrane, which is 0.0178 ; is the membrane conductivity, which is 0.14 .

[0035] Can be used as electrical power for hydrogen production by electrolysis , input into the proton exchange membrane electrolyzer, satisfy: (6) The proton exchange membrane electrolyzer produces hydrogen during operation. The hydrogen production per unit time is (unit: )for: (7) After hydrogen is produced by electrolysis, electrical energy is converted into chemical energy, generating the power of chemical energy. : (8) In the formula, The combustion enthalpy of hydrogen combustion to generate liquid water, that is, the standard formation enthalpy of liquid water, is -285.83 .

[0036] Therefore, the energy conversion efficiency of the proton exchange membrane electrolysis module is (9) Step 2: If Figure 3 As shown, a hydrogen storage device model is established, including hydrogen storage balance constraints, upper and lower limit constraints of hydrogen storage capacity, upper and lower limit constraints of hydrogen storage tank input and output, etc. The hydrogen storage tank model is expressed as follows: (10) (11) (12) (13) Where: is the hydrogen storage capacity of the hydrogen storage tank at time t; and They are the input and output hydrogen power of the hydrogen storage tank at time t respectively; and They are the storage and release efficiency of hydrogen storage tanks respectively; and They are the minimum and maximum capacities of hydrogen storage tanks respectively; , They are the minimum and maximum hydrogen storage power of the hydrogen storage tank respectively; , They are the minimum and maximum hydrogen discharge power of the hydrogen storage tank respectively; It is a 0-1 variable that characterizes the storage and release status of the hydrogen storage tank.

[0037] Step 3: Establish a hydrogen fuel cell model that can realize the conversion of hydrogen energy into electrical energy, taking into account the operating temperature, conversion efficiency, power regulation flexibility, etc. of the fuel cell. Here, the proton exchange membrane fuel cell (PEMFC) is selected, and its model is as follows: Hydrogen undergoes oxidation reaction at the negative electrode of PEMFC:

[0038] Oxygen reduction reaction occurs at the positive electrode of the proton exchange membrane fuel cell:

[0039] The overall chemical reaction formula of the fuel cell is:

[0040] The fuel cell can be regarded as a DC power supply. The voltage provided by a single fuel cell is , and its calculation formula is: (14) In the formula, is the open circuit voltage of the proton exchange membrane fuel cell, is the activation loss voltage, which is related to the activation loss at low current density and is used to drive the electrochemical reaction. is the ohmic loss voltage of PEMFC, which is related to the voltage loss due to contact resistance, etc. is the concentration loss voltage, which is related to the uneven concentration produced when the reactants are consumed rapidly. Its calculation formulas are: (15) (16) (17) (18) In the formula, is the operating temperature of the fuel cell. PEMFC generally operates at room temperature ~100 degrees Celsius; is the nominal operating temperature, which is 296K; and The partial pressures of oxygen and hydrogen are 1 atm respectively; is the current density, satisfying: (19) In the formula, is the current flowing through the fuel cell, is the effective membrane area of ​​a single fuel cell, taken as 61 .

[0041] have The total electrical power generated by the fuel cells running in series is: (20) The rate at which PEMFC consumes hydrogen is: (twenty one) PEMFC Total power generated by chemical reactions: (twenty two) like Figure 4 As shown in the figure, part of the total energy released by the chemical reaction is converted into electrical energy through the fuel cell, and some is converted into other forms such as heat during the reaction. Suppose the proportion of chemical energy released by the reaction that can be used for fuel cell power generation is .

[0042] The energy conversion efficiency of a fuel cell is: (twenty three) Step 4: Establish the power flow balance constraint of the power grid. The active power balance constraint of the distribution network can be expressed as: (twenty four) (25) In the formula, The power generation load of various power generating units (including power transmission from the upper power grid, local traditional units, and local renewable energy units); is the grid load; , Represents the distribution network nodes The upper and lower limits of the unit's power generation capacity.

[0043] Step 5: Construct an optimal configuration model with the goal of optimizing economic cost. The economic cost includes construction cost and annual operation and maintenance cost. The model is as follows: The objective function includes the equal annual value investment cost and operation and maintenance cost: (26) (27) (28) (29) Where: , , and They are comprehensive equivalent annual cost, investment cost, maintenance cost and operating cost; It is a collection of other generating units such as photovoltaic and wind power; is the capital recovery coefficient; is the discount rate; For equipment The operating life of , , and are the unit capacity investment costs of equipment k, electrolyzer, hydrogen storage tank and hydrogen fuel cell respectively; , , and are the annual maintenance costs per unit capacity of equipment k, electrolyzer, hydrogen storage tank and hydrogen fuel cell respectively; , , and are the planned capacities of equipment k, electrolyzer, hydrogen storage tank and hydrogen fuel cell respectively.

[0044] Annual operating costs Including fuel costs, electricity purchase and sales costs, and wind and solar power abandonment costs, it can be expressed as follows: (30) Where: , and They are the annual fuel cost, electricity purchase and sales cost, and annual penalty cost for abandoned wind and solar power.

[0045] The operating costs of hydrogen energy storage include the operating costs of electrolyzers, hydrogen storage tanks and hydrogen fuel cells: (31) (32) (33) (34) Where: , and are the operating costs of the electrolyzer, hydrogen storage tank, and hydrogen fuel cell, respectively; , and They are the unit operating cost coefficients of hydrogen production from electricity, hydrogen storage tanks and hydrogen fuel cell power generation respectively.

[0046] Furthermore, in step 1, an electrolyzer model for the electrolytic hydrogen production process was established. A proton exchange membrane electrolysis (PEMEC) device with high efficiency, medium cost, fast response speed and good flexibility was selected as the modeling object. During the modeling process, parameters such as the reversible voltage, electrode overvoltage, and ohmic overvoltage of the electrolysis process were considered.

[0047] Furthermore, in step 2, a hydrogen storage device model is established. Considering the constraints of hydrogen storage balance, upper and lower limits of hydrogen storage capacity, upper and lower limits of hydrogen storage tank input and output, etc., the hydrogen storage tank performs hydrogen storage or hydrogen release operations in a certain period of time.

[0048] Furthermore, in step 3, a hydrogen fuel cell model that can realize the conversion of hydrogen energy into electrical energy is established. Based on comprehensive consideration of the operating temperature, conversion efficiency, power regulation flexibility, etc. of the fuel cell, the proton exchange membrane fuel cell (PEMFC) is selected as the modeling object.

[0049] Furthermore, the grid flow balance constraint is established in step 4. The active power of the distribution network node should satisfy the input-output balance, taking into account the power of various generator sets, grid flow, load and energy bidirectional conversion.

[0050] Furthermore, in step 5, an optimization configuration model with the goal of optimal economic cost is established. The construction cost and annual operation and maintenance cost of electrolyzers, hydrogen storage tanks, hydrogen fuel cells and other devices are considered, among which the investment and construction cost is converted into the equivalent annual investment cost, and the operation and maintenance cost includes the annual maintenance cost of equipment, fuel cost, electricity purchase and sales cost and annual wind and solar power abandonment penalty cost.

[0051] The present invention is further described below through a specific embodiment.

[0052] 1. Establish an electrolyzer model that can realize the electrolytic hydrogen production process, taking the proton exchange membrane electrolysis (PEMEC) device as the modeling object. The model is as follows: (35) in: is the voltage across a single electrolytic cell. The electrolysis reaction in PEMEC is not spontaneous. is the minimum starting voltage of the reaction (i.e., reversible voltage), is the electrode overvoltage, is the ohmic overvoltage; It is the operating temperature of the proton exchange membrane electrolyzer, which is generally between 60 and 80 degrees Celsius; is the ideal gas constant, take 8.314 ; is the Faraday constant, take 96485 ; represents the hydrogen partial pressure at the cathode of the electrolyzer, which is 6.9 ; represents the oxygen partial pressure at the anode of the electrolytic cell, taking 1.3 ; is the anode current density, ; is the cathode current density, ; is the current density of the proton exchange membrane electrolyzer, which is the ratio of the current flowing through the proton exchange membrane electrolyzer to the effective area of ​​the electrolyzer; is the current flowing through the proton exchange membrane electrolyzer, is the effective area of ​​a single electrolytic cell, taken as 212.5 ; is the thickness of the proton exchange membrane, which is 0.0178 ; is the membrane conductivity, which is 0.14 ; is the electrical power that can be used to produce hydrogen by electrolysis; is the amount of hydrogen produced per unit time (unit: ); Power to produce chemical energy for the electrolyzer; is the combustion enthalpy of hydrogen combustion to produce liquid water; is the energy conversion efficiency of the proton exchange membrane electrolysis module.

[0053] 2. Establish a hydrogen storage device model, including hydrogen storage balance constraints, hydrogen storage capacity upper and lower limit constraints, hydrogen storage tank input and output upper and lower limit constraints, etc. The model is as follows: (36) in: is the hydrogen storage capacity of the hydrogen storage tank at time t; and They are the input and output hydrogen power of the hydrogen storage tank at time t respectively; and They are the storage and release efficiency of hydrogen storage tanks respectively; and They are the minimum and maximum capacities of hydrogen storage tanks respectively; , They are the minimum and maximum hydrogen storage power of the hydrogen storage tank respectively; , They are the minimum and maximum hydrogen discharge power of the hydrogen storage tank respectively; It is a 0-1 variable that characterizes the storage and release status of the hydrogen storage tank.

[0054] 3. Establish a hydrogen fuel cell model that can realize the conversion of hydrogen energy into electrical energy, and the modeling object is the proton exchange membrane fuel cell (PEMFC). The model is as follows: (37) Where: is the open circuit voltage of the proton exchange membrane fuel cell; is the activation loss voltage, which is related to the activation loss at low current density and is used to drive the electrochemical reaction; is the ohmic loss voltage of PEMFC, which is related to the voltage loss on contact resistance, etc.; is the concentration loss voltage, which is related to the uneven concentration produced when the reactants are consumed rapidly; is the operating temperature of the fuel cell. PEMFC generally operates at room temperature ~100 degrees Celsius; is the nominal operating temperature, which is 296K; and The partial pressures of oxygen and hydrogen are 1 atm respectively; is the current density; is the current flowing through the fuel cell; is the effective membrane area of ​​a single fuel cell, taken as 61 ; is the number of parallel fuel cells; is the total electrical power emitted; is the energy conversion efficiency of the fuel cell. 4. Establish active power balance constraints of distribution network. The model is as follows: (38) In the formula, The power generation load of various power generating units (including power transmission from the upper power grid, local traditional units, and local renewable energy units); is the grid load; , Represents the distribution network nodes The upper and lower limits of the generating capacity of the unit; Indicates the power flow of power grid 1.

[0055] 5. Construct an optimization configuration model with the goal of optimizing economic costs. Economic costs include construction costs and annual operation and maintenance costs. The investment and construction costs are converted into annual investment costs, and the operation and maintenance costs include the annual maintenance costs of equipment, fuel costs, electricity purchase and sales costs, and annual wind and solar power abandonment penalty costs. The objective function is as follows: (39) Where: , , and They are comprehensive equivalent annual cost, investment cost, maintenance cost and operating cost; It is a collection of other generating units such as photovoltaic and wind power; is the capital recovery coefficient; is the discount rate; For equipment The operating life of , , and are the unit capacity investment costs of equipment k, electrolyzer, hydrogen storage tank and hydrogen fuel cell respectively; , , and are the annual maintenance costs per unit capacity of equipment k, electrolyzer, hydrogen storage tank and hydrogen fuel cell respectively; , , and are the planned capacities of equipment k, electrolyzer, hydrogen storage tank and hydrogen fuel cell respectively; , and They are annual fuel cost, electricity purchase and sales cost, and annual penalty cost for abandoned wind and solar power. , and are the operating costs of the electrolyzer, hydrogen storage tank, and hydrogen fuel cell, respectively; , and They are the unit operating cost coefficients of hydrogen production from electricity, hydrogen storage tanks and hydrogen fuel cell power generation respectively.

[0056] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware.

[0057] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for optimizing the configuration of medium- and long-term energy storage in a distribution network considering bidirectional conversion of energy, characterized in that: The following steps are involved: Producing hydrogen by electrolysis using a proton exchange membrane electrolyzer, wherein the proton exchange membrane electrolyzer model is based on reversible voltage, electrode overvoltage and ohmic overvoltage to produce hydrogen using electrical energy; Modeling a hydrogen storage device, wherein the hydrogen storage device model sets a hydrogen storage balance constraint, an upper and lower limit constraint of the hydrogen storage capacity, and an input and output power constraint of the hydrogen storage tank; A hydrogen fuel cell model is constructed based on a proton exchange membrane fuel cell, wherein the proton exchange membrane fuel cell model converts hydrogen energy into electrical energy through an electrochemical reaction of hydrogen, and outputs electrical energy by taking into account operating temperature, conversion efficiency, and power regulation flexibility; Ensure that the active power output and input of each node in the distribution network are balanced. The power flow balance model comprehensively considers the power of local power generation, renewable energy access and bidirectional energy conversion; With the goal of optimizing economic costs, the capacity configuration of the energy storage system is optimized by combining the construction cost and annual operation and maintenance cost of the proton exchange membrane electrolyzer, hydrogen storage device and proton exchange membrane fuel cell.

2. The method for optimizing the configuration of medium- and long-term energy storage in a distribution network considering bidirectional conversion of energy according to claim 1 is characterized in that: The voltage across the proton exchange membrane electrolyzer is calculated by the following formula: in, is the voltage across a single electrolytic cell; is the reversible voltage; is the electrode overvoltage; is an ohmic overvoltage.

3. The method for optimizing the configuration of medium- and long-term energy storage in a distribution network considering bidirectional conversion of energy according to claim 2 is characterized in that: The reversible voltage of the proton exchange membrane electrolyzer is calculated by the following formula: in, is the operating temperature of the proton exchange membrane electrolyzer, which ranges from 60 to 80 degrees Celsius; is the ideal gas constant, take 8.314 ; is the Faraday constant, take 96485 ; represents the hydrogen partial pressure at the cathode of the electrolyzer, which is 6.9 ; represents the oxygen partial pressure at the anode of the electrolytic cell, taking 1.3 .

4. The method for optimizing the configuration of medium- and long-term energy storage in a distribution network considering bidirectional conversion of energy according to claim 1 is characterized in that: The hydrogen storage balance constraint of the hydrogen storage device model is calculated by the following formula: in, is the hydrogen storage capacity of the hydrogen storage tank at time t; and They are the input and output hydrogen power of the hydrogen storage tank at time t respectively; and They are the storage and release efficiency of the hydrogen storage tank respectively.

5. The method for optimizing the configuration of medium- and long-term energy storage in a distribution network considering bidirectional conversion of energy according to claim 1 is characterized in that: The electrical energy output power of the proton exchange membrane fuel cell model is calculated by the following formula: In the formula, is the open circuit voltage of the proton exchange membrane fuel cell; is the activation loss voltage, which is related to the activation loss at low current density and is used to drive the electrochemical reaction; It is the ohmic loss voltage of the proton exchange membrane fuel cell, which is related to the voltage loss on the contact resistance, etc. It is the concentration loss voltage, which is related to the uneven concentration produced when the reactants are consumed rapidly.

6. The method for optimizing the configuration of medium- and long-term energy storage in a distribution network considering bidirectional conversion of energy according to claim 1 is characterized in that: The energy conversion efficiency of the proton exchange membrane fuel cell is calculated by the following formula: in, is the rate at which the proton exchange membrane fuel cell consumes hydrogen; Indicates that there is The total electrical power generated by the proton exchange membrane fuel cells operating in series is: It is the total power generated by the chemical reaction of the proton exchange membrane fuel cell.

7. The method for optimizing the configuration of medium- and long-term energy storage in a distribution network considering bidirectional conversion of energy according to claim 1 is characterized in that: The economic cost objective function of the optimization configuration model is calculated by the following formula: in, , , and They are comprehensive equivalent annual cost, investment cost, maintenance cost and operating cost; It is the operating cost of hydrogen energy storage.

8. The method for optimizing the configuration of medium- and long-term energy storage in a distribution network considering bidirectional conversion of energy according to claim 7 is characterized in that: The economic cost objective function also includes the penalty cost for abandoning wind and solar power.

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