Electricity-hydrogen comprehensive energy system reliability evaluation method based on electricity-hydrogen conversion equipment aging failure model

Abstract

The invention discloses an electricity-hydrogen comprehensive energy system reliability evaluation method based on an electricity-hydrogen conversion equipment aging failure model. The method comprises the following steps: 1) establishing an electricity-hydrogen conversion equipment operation model; 2) establishing an electricity-hydrogen conversion equipment aging failure reliability model considering membrane electrode degradation; 3) constructing an optimal load reduction model of the electricity-hydrogen comprehensive energy system considering aging failure of the electricity-hydrogen conversion equipment; 4) constructing a power supply reliability reduction rate expression and a hydrogen supply reliability reduction rate expression as aging energy supply reliability evaluation indexes of the electric hydrogen comprehensive energy system; and 5) solving the optimal load reduction model under all the system operation states, calculating a system reliability evaluation index, and evaluating the reliability level of the electricity-hydrogen comprehensive energy system. According to the method, the influence of aging failure of the electricity-hydrogen conversion equipment on the power supply reliability and hydrogen supply reliability of the electricity-hydrogen comprehensive energy system is quantified, and the reliability level of the electricity-hydrogen comprehensive energy system can be accurately evaluated.

Description

Technical Field

[0001] The present invention relates to the field of reliability assessment of electric power systems, and in particular to a reliability assessment method for an electric-hydrogen integrated energy system based on an aging failure model of electric-hydrogen conversion equipment. Background Art

[0002] The electric-hydrogen integrated energy system can fully utilize the low-carbon and flexible characteristics of hydrogen energy, and plays a key role in strengthening energy security and improving sustainable power supply capabilities. It is an important support for building a new power system. By evaluating the reliability of the electric-hydrogen integrated energy system, theoretical support and decision-making basis can be provided for the stable operation and scientific planning of the electric-hydrogen integrated energy system.

[0003] In terms of reliability modeling of electric-hydrogen conversion equipment, the reliability model of electric-hydrogen conversion equipment is the basis for reliability assessment of electric-hydrogen integrated energy systems. In actual operation, electrolyzers and hydrogen fuel cells are key equipment for energy coupling and electric-hydrogen conversion in electric-hydrogen integrated energy systems. Their failure states are closely related to the electrochemical reaction processes of the internal components of the equipment. The aging failure state of system equipment is an irreparable failure state, which has an important impact on the reliable operation of electric-hydrogen integrated energy systems. Therefore, aging failures cannot be ignored during the commissioning of equipment. However, existing studies have not considered the impact of electrochemical reaction losses of electrolyzers and hydrogen fuel cells on aging failure rates during operation, and are unable to accurately assess the reliability of electric-hydrogen integrated energy systems.

[0004] In terms of reliability assessment of integrated electric-hydrogen energy systems, existing studies have not considered the impact of aging and failure of electric-hydrogen conversion equipment on the reliability of power supply and hydrogen supply of the system. There is a lack of aging energy supply reliability assessment indicators that consider the aging and failure of electric-hydrogen conversion equipment. There is no reliability assessment method for integrated electric-hydrogen energy systems based on the aging and failure model of electric-hydrogen conversion equipment.

[0005] In summary, it is urgent to establish an aging failure reliability model of electric-hydrogen conversion equipment considering membrane electrode degradation based on the operation mechanism of electric-hydrogen conversion equipment, propose aging energy supply reliability evaluation indicators considering aging failure of electric-hydrogen conversion equipment, and propose a reliability evaluation method for electric-hydrogen integrated energy system based on the aging failure model of electric-hydrogen conversion equipment. Summary of the invention

[0006] The purpose of the present invention is to provide a reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, comprising the following steps:

[0007] 1) Based on the electricity-hydrogen conversion and energy coupling process of the electricity-hydrogen integrated energy system, establish an operation model of the electricity-hydrogen conversion equipment;

[0008] 2) Establish an aging failure reliability model for electric-hydrogen conversion equipment considering membrane electrode degradation;

[0009] 3) Construct an optimal load reduction model for the electric-hydrogen integrated energy system considering the aging and failure of electric-hydrogen conversion equipment;

[0010] 4) Construct the expressions of power supply reliability reduction rate and hydrogen supply reliability reduction rate as the evaluation indicators of aging energy supply reliability of the electric-hydrogen integrated energy system;

[0011] 5) Solve the optimal load reduction model under all system operating conditions, calculate the system reliability evaluation index, and evaluate the reliability level of the electric-hydrogen integrated energy system.

[0012] Furthermore, the electric-to-hydrogen conversion equipment operation model includes a proton exchange membrane electrolyzer operation model and a proton exchange membrane fuel cell operation model.

[0013] Further, the operation model of the proton exchange membrane electrolyzer is as follows:

[0014] E PEMWE =E rev +E act +E ohm (1)

[0015] In the formula, E rev is the reversible voltage, E act 、E ohm They are activation voltage, ohmic voltage and E PEMWE is the operating voltage of the proton exchange membrane electrolyzer;

[0016] Among them, the reversible voltage E rev As shown below:

[0017] ΔG=ΔH-T·ΔS (2)

[0018]

[0019] In the formula, T is temperature; ΔS is entropy, ΔH is enthalpy; n is the number of electrons transferred to generate 1 mole of hydrogen; F is the Faraday constant; ΔG is the intermediate parameter;

[0020] Activation voltage E act As shown below:

[0021] E act =E act,a +E act,c (4)

[0022]

[0023] Where R is the gas reaction constant; z is the stoichiometric coefficient of water electrolysis; α a , α c is the charge transfer coefficient; i a 、ic is the anode current and cathode current of the electrolytic cell; E act,a 、E act,c are the anode voltage and cathode voltage of the electrolytic cell; i 0,a 、i 0,c are the anode initial current and cathode initial current of the electrolytic cell;

[0024] Ohm voltage E ohm As shown below:

[0025] E ohm =E ohm,mem +E ohm,ele =R mem ·i0+R ele ·i0 (6)

[0026] In the formula, E ohm,mem 、E ohm,ele is the voltage of the membrane resistor and the voltage of the electronic resistor; i0 is the current; R mem , R ele It is the membrane resistance and electronic resistance;

[0027] Membrane resistance R mem As shown below:

[0028]

[0029] τ=0.08533T-6.77632

[0030] In the formula, is the initial thickness of the membrane, σ0 is the initial conductivity of the membrane, and τ is the humidification degree of the membrane;

[0031] The calculation formula for the attenuation of membrane thickness and conductivity over operating time is as follows:

[0032]

[0033] In the formula, F R is the fluoride release rate, ρ f is the fluoride content ratio of the membrane, ρ M is the film density. t is the time; σ is the film thickness and conductivity;

[0034] The resistance change caused by the loss of electronic materials is calculated as follows

[0035] R ele (t) = R0 + b R t (10)

[0036] Where R0 is the initial resistance value, b R is the degradation rate of the resistor material. ele(t) is the electronic resistance at time t.

[0037] Further, the operation model of the proton exchange membrane fuel cell is as follows:

[0038] E PEMFC =E rev -E act -E ohm (11)

[0039] In the formula, E act 、E ohm is the activation polarization loss and ohmic polarization loss; E rev is the reversible voltage; E PEMFC Output voltage for proton exchange membrane fuel cell;

[0040] Among them, the reversible voltage E rev As shown below:

[0041] ΔG=ΔH-T·ΔS (12)

[0042]

[0043] In the formula, T is temperature; ΔS is entropy, ΔH is enthalpy; n is the number of electrons transferred to generate 1 mole of hydrogen; F is the Faraday constant; ΔG is the intermediate parameter;

[0044] Activation polarization loss E act As shown below:

[0045] E act =E act,a +E act,c (14)

[0046]

[0047] Where R is the gas reaction constant; z is the stoichiometric coefficient of water electrolysis; α a , α c is the charge transfer coefficient; i a 、i c is the anode current and cathode current of the fuel cell; E act,a 、E act,c are the anode voltage and cathode voltage of the fuel cell; i 0,a 、i 0,c are the anode initial current and cathode initial current of the fuel cell;

[0048] Ohmic polarization loss E ohm As shown below:

[0049] E ohm =E ohm,mem +E ohm,ele =Rmem ·i0+R ele ·i0 (16)

[0050] In the formula, E ohm,mem 、E ohm,ele is the voltage of the membrane resistor and the voltage of the electronic resistor; i0 is the current; R mem , R ele It is the membrane resistance and electronic resistance;

[0051] Membrane resistance R mem As shown below:

[0052]

[0053] τ=0.08533T-6.77632

[0054] In the formula, is the initial thickness of the membrane, σ0 is the initial conductivity of the membrane, and τ is the humidification degree of the membrane.

[0055] The calculation formula for the attenuation of membrane thickness and conductivity with operating time is as follows

[0056]

[0057] In the formula, F R is the fluoride release rate, ρ f is the fluoride content ratio of the membrane, ρ M is the film density; σ is the film thickness and conductivity; t is the time;

[0058] Electronic resistance R ele As shown below:

[0059] R ele (t) = R0 + b R t (20)

[0060] Where R0 is the initial resistance value, b R is the degradation rate of the resistor material. ele (t) is the electronic resistance at time t.

[0061] Furthermore, the reliability model of aging failure of electric-hydrogen conversion equipment is as follows:

[0062] U=U0+U age -U0U age (twenty one)

[0063] Where U is the total unavailability rate of the equipment, and U0 is the unavailability rate of repairable failure;

[0064] Among them, the aging failure unavailability rate of hydrogen energy equipment U ageAs shown below:

[0065]

[0066] Where λ is the equipment aging failure rate, and μ is the equipment repair rate.

[0067] The aging failure rate λ based on the Weibull distribution is as follows:

[0068]

[0069]

[0070] Wherein, E is the operating voltage of the electric-to-hydrogen conversion device, E0 is the electrochemical reaction voltage defined by Gibbs free energy inside the electric-to-hydrogen conversion device; β is the shape parameter, η is the proportional parameter, and D is the degradation rate of the operating voltage of the electric-to-hydrogen conversion device caused by membrane electrode degradation.

[0071] Furthermore, the objective function f of the optimal load reduction model of the electric-hydrogen integrated energy system considering the aging and failure of the electric-hydrogen conversion equipment is as follows:

[0072]

[0073] In the formula, c DG is the unit penalty cost for abandoning wind and solar power; Ω WG ,Ω PV are the grid-connected node sets of wind and solar generators respectively; ΔP WG,it , ΔP PV,it are the abandoned wind and solar power respectively; T is the dispatching period; n is the number of nodes; Z is the set of load types supplied by the electric-hydrogen integrated energy system, including electric and hydrogen loads; c z The penalty cost for unit reduction of the load of class z; L z,it is the power reduction of the z-th load; the subscripts i and t represent the node and time respectively. Δt is the time step.

[0074] Furthermore, the constraints of the optimal load reduction model of the electric-hydrogen integrated energy system considering the aging and failure of the electric-hydrogen conversion equipment include the operation constraints of the proton exchange membrane fuel cell, the operation constraints of the relationship between the hydrogen consumption and output power of the fuel cell, the operation constraints of the proton exchange membrane electrolyzer, the operation constraints of the relationship between the hydrogen production and power consumption of the electrolyzer, the electric power balance constraints, and the hydrogen balance constraints.

[0075] Furthermore, the PEM fuel cell operation constraints are as follows:

[0076]

[0077] In the formula, m FC,t is the hydrogen consumption of the fuel cell at time t, P FC,tis the power generated by the fuel cell at time t; N fc is the number of fuel cells connected in series and parallel; I fc,t is the working current of the fuel cell; k1 and k2 are conversion coefficients; F is the Faraday constant; E PEMFC,t is the output voltage of the proton exchange membrane fuel cell at time t;

[0078] The operating constraints of the fuel cell's hydrogen consumption and output power are as follows:

[0079] Q FC,it =ρ H2 m FC,it (28)

[0080] P FC,it =g(m FC,it ) (29)

[0081] μ FC,it Q FC,min ≤Q FC,it ≤μ FC,it Q FC,max (30)

[0082] In the formula, μ FC,it is the start-stop state variable of the fuel cell. If it is 1, it indicates the start state, and if it is 0, it indicates the stop state; Q FC,max , Q FC,min The hydrogen consumption of the fuel cell is Q FC,it The upper and lower limits of H2 is the standard density of hydrogen; P FC,it is the active power output of the fuel cell; m FC,it is the hydrogen consumption of the fuel cell; g(m FC,it ) is the relationship function between the active power of the fuel cell and the hydrogen consumption;

[0083] The operating constraints of the proton exchange membrane electrolyzer are as follows:

[0084] P EL,t =k1N el E PEMWE,t I el,t (31)

[0085]

[0086] Where P EL,t is the power consumption at time t, m EL,t is the hydrogen production at time t, N el is the number of electrolytic cells connected in series and parallel, P EL,it I is the active power consumed by the electrolytic cell; el,t is the working current of the electrolytic cell; E PEMWE,tis the operating voltage of the proton exchange membrane electrolyzer at time t, η f is the number of connected electrolytic cells;

[0087] The operating constraints of the electrolyzer on the relationship between hydrogen production and power consumption are as follows:

[0088]

[0089] μ EL,it P EL,min ≤P EL,it ≤μ EL,it P EL,max (34)

[0090] In the formula, ρ H2 is the standard density of hydrogen; μ EL,it is the start-stop state variable of the electrolytic cell. If it is 1, it indicates the start state, and if it is 0, it indicates the stop state; P EL,max and P EL,min The power consumption of the electrolytic cell is P EL,it The upper and lower limits of Q is the relationship between the hydrogen production and power consumption of the electrolyzer; EL,it is the hydrogen production of the electrolyzer;

[0091] The electrical power balance constraints are as follows:

[0092]

[0093] Where P GEN,it P is the active power output by the generator set; WG,it , P PV,it are the active power actually output by the wind and solar units; P FC,it , P EL,it are the active power output by the fuel cell and the active power consumed by the electrolyzer; P load,it , L p,it are the active load and load reduction power respectively; B is the node susceptance matrix used for DC power flow calculation, and θ is the node voltage phase angle.

[0094] The hydrogen balance constraints are as follows:

[0095] Q DP,in,it =Q EL,it -Q HT,in,it +Q HT,out,it -Q FC,it (36)

[0096] Q DP,out,it =Q load,it -L q,it (37)

[0097] In the formula, QDP,in,it , Q DP,out,it are the amount of hydrogen input and output of the hydrogenation unit; Q EL,it , Q FC,it are the hydrogen production of the electrolyzer and the hydrogen consumption of the fuel cell; Q HT,in,it , Q HT,out,it are the hydrogen filling and dehydration amounts of the hydrogen storage tank respectively; Q load,it , L q,it They are the demand and reduction of hydrogen load respectively.

[0098] Furthermore, the power supply reliability reduction rate R ESR As shown below:

[0099]

[0100] In the formula, EENS age and EENS0 are the expected energy shortage of the electric load of the electric-hydrogen integrated energy system before and after the aging and failure of the electric-hydrogen conversion equipment.

[0101] Hydrogen supply reliability reduction rate R HSR As shown below:

[0102]

[0103] Where, EHNS age and EHNS0 are the expected hydrogen load shortage energy of the electric-hydrogen integrated energy system before and after aging and failure of the electric-hydrogen conversion equipment.

[0104] Further, in step 5), the step of calculating the system reliability evaluation index and evaluating the reliability level of the electric-hydrogen integrated energy system includes:

[0105] 5.1) Input the relevant data of the electric-hydrogen integrated energy system and equipment parameters, and initialize the operating status of all equipment;

[0106] 5.2) System operation status obtained through Monte Carlo simulation sampling;

[0107] 5.3) Initialize simulation time d = 1 and simulation years N y =1;

[0108] 5.4) Obtain the system state at the dth moment, solve the optimal load reduction model of the electric-hydrogen integrated energy system, and obtain the load reduction state and optimal load reduction amount at that moment;

[0109] 5.5) If d>8760, go to step 5.6), otherwise let d=d+1 and go to step 5.4);

[0110] 5.6) Calculate the Nth yThe reliability evaluation index of aging energy supply of electric-hydrogen integrated energy system in 2018 is set as y =N y +1;

[0111] 5.7) If N y >20000 or the variance ε of the expected value of system load reduction index <0.05, go to step 5.8), otherwise set d = 1 and go to step 5.4);

[0112] 5.8) Reliability evaluation indicators of output electricity-hydrogen integrated energy system.

[0113] The technical effect of the present invention is unquestionable. The aging failure reliability model of the electric-hydrogen conversion equipment considering the membrane electrode degradation proposed in the present invention will help to further improve the accuracy of the assessment of the reliability level of the electric-hydrogen energy load supply of the electric-hydrogen integrated energy system.

[0114] Starting from the perspective of aging and failure of electric-hydrogen conversion equipment, the present invention proposes aging energy supply reliability evaluation indicators for electric-hydrogen integrated energy systems, including power supply reliability reduction rate and hydrogen supply reliability reduction rate, and further proposes an optimal load reduction model for electric-hydrogen integrated energy systems that takes into account aging and failure of electric-hydrogen conversion equipment. The present invention quantitatively evaluates the reliability of electric-hydrogen integrated energy systems based on the Monte Carlo method, verifies that the aging effect of electric-hydrogen conversion equipment cannot be ignored in reliability evaluation, and quantifies the impact of aging and failure of electric-hydrogen conversion equipment on the power supply reliability and hydrogen supply reliability of electric-hydrogen integrated energy systems, which helps to accurately evaluate the reliability level of electric-hydrogen integrated energy systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0115] Figure 1 This is a schematic diagram of the structure of the electric-hydrogen integrated energy system;

[0116] Figure 2 (a) is a structural diagram of a proton exchange membrane electrolyzer; Figure 2 (b) is a structural diagram of a proton exchange membrane fuel cell;

[0117] Figure 3 It is a flowchart of the reliability assessment method;

[0118] Figure 4 (a)- Figure 4 (d) is the simulation result, where Figure 4 (a) To take into account the impact of aging failure on system LOELP; Figure 4 (b) To take into account the impact of aging failure on the system EENS; Figure 4 (c) To take into account the impact of aging failure on the system LOHLP; Figure 4 (d) To take into account the impact of aging failure on the system EHNS. DETAILED DESCRIPTION

[0119] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0120] Embodiment 1:

[0121] See also Figures 1 to 4 , a reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, comprising the following steps:

[0122] 1) Based on the electricity-hydrogen conversion and energy coupling process of the electricity-hydrogen integrated energy system, establish an operation model of the electricity-hydrogen conversion equipment;

[0123] 2) Establish an aging failure reliability model for electric-hydrogen conversion equipment considering membrane electrode degradation;

[0124] 3) Construct an optimal load reduction model for the electric-hydrogen integrated energy system considering the aging and failure of electric-hydrogen conversion equipment;

[0125] 4) Construct the expressions of power supply reliability reduction rate and hydrogen supply reliability reduction rate as the evaluation indicators of aging energy supply reliability of the electric-hydrogen integrated energy system;

[0126] 5) Solve the optimal load reduction model under all system operating conditions, calculate the system reliability evaluation index, and evaluate the reliability level of the electric-hydrogen integrated energy system.

[0127] Embodiment 2:

[0128] A reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, the technical content of which is the same as that of Example 1, and further, the electric-hydrogen conversion equipment operation model includes a proton exchange membrane electrolyzer operation model and a proton exchange membrane fuel cell operation model.

[0129] Embodiment 3:

[0130] A reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, the technical content of which is the same as any one of Embodiments 1-2, and further, the operation model of a proton exchange membrane electrolyzer is as follows:

[0131] E PEMWE =E rev +E act +E ohm (1)

[0132] In the formula, E rev is the reversible voltage, E act 、E ohmThey are activation voltage, ohmic voltage and E PEMWE is the operating voltage of the proton exchange membrane electrolyzer;

[0133] Among them, the reversible voltage E rev As shown below:

[0134] ΔG=ΔH-T·ΔS (2)

[0135]

[0136] In the formula, T is temperature; ΔS is entropy, ΔH is enthalpy; n is the number of electrons transferred to generate 1 mole of hydrogen; F is the Faraday constant; ΔG is the intermediate parameter;

[0137] Activation voltage E act As shown below:

[0138]

[0139] Where R is the gas reaction constant; z is the stoichiometric coefficient of water electrolysis; α a , α c is the charge transfer coefficient; i a 、i c is the anode current and cathode current of the electrolytic cell; E act,a 、E act,c are the anode voltage and cathode voltage of the electrolytic cell; i 0,a 、i 0,c are the anode initial current and cathode initial current of the electrolytic cell;

[0140] Ohm voltage E ohm As shown below:

[0141] E ohm =E ohm,mem +E ohm,ele =R mem ·i0+R ele ·i0 (6)

[0142] In the formula, E ohm,mem 、E ohm,ele is the voltage of the membrane resistor and the voltage of the electronic resistor; i0 is the current; R mem , R ele It is the membrane resistance and electronic resistance;

[0143] Membrane resistance R mem As shown below:

[0144]

[0145] τ=0.08533T-6.77632

[0146] In the formula, is the initial thickness of the membrane, σ0 is the initial conductivity of the membrane, and τ is the humidification degree of the membrane;

[0147] As the electrochemical reaction proceeds, the membrane and electrode materials will be lost, resulting in an increase in ohmic voltage and a decrease in the performance of the electrolyzer. The calculation formula for the attenuation of membrane thickness and conductivity over operating time is as follows:

[0148]

[0149] In the formula, F R is the fluoride release rate, ρ f is the fluoride content ratio of the membrane, ρ M is the film density. t is the time; σ is the film thickness and conductivity;

[0150] The calculation formula for the resistance change caused by the loss of electronic materials such as electrodes is as follows

[0151] R ele (t) = R0 + b R t (10)

[0152] Where R0 is the initial resistance value, b R is the degradation rate of the resistor material. ele (t) is the electronic resistance at time t.

[0153] Embodiment 4:

[0154] A reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, the technical content of which is the same as any one of Embodiments 1-3, and further, a proton exchange membrane fuel cell operation model is as follows:

[0155] E PEMFC =E rev -E act -E ohm (11)

[0156] In the formula, E act 、E ohm is the activation polarization loss and ohmic polarization loss; E rev is the reversible voltage; E PEMFC Output voltage for proton exchange membrane fuel cell;

[0157] Among them, the reversible voltage E rev As shown below:

[0158] ΔG=ΔH-T·ΔS (12)

[0159]

[0160] In the formula, T is temperature; ΔS is entropy, ΔH is enthalpy; n is the number of electrons transferred to generate 1 mole of hydrogen; F is the Faraday constant; ΔG is the intermediate parameter;

[0161] Activation polarization loss E act As shown below:

[0162] E act =E act,a +E act,c (14)

[0163]

[0164] Where R is the gas reaction constant; z is the stoichiometric coefficient of water electrolysis; α a , α c is the charge transfer coefficient; i a 、i c is the anode current and cathode current of the fuel cell; E act,a 、E act,c are the anode voltage and cathode voltage of the fuel cell; i 0,a 、i 0,c are the anode initial current and cathode initial current of the fuel cell;

[0165] Ohmic polarization loss E ohm As shown below:

[0166] E ohm =E ohm,mem +E ohm,ele =R mem ·i0+R ele ·i0 (16)

[0167] In the formula, E ohm,mem 、E ohm,ele is the voltage of the membrane resistor and the voltage of the electronic resistor; i0 is the current; R mem , R ele It is the membrane resistance and electronic resistance;

[0168] Membrane resistance R mem As shown below:

[0169]

[0170] τ=0.08533T-6.77632

[0171] In the formula, is the initial thickness of the membrane, σ0 is the initial conductivity of the membrane, and τ is the humidification degree of the membrane.

[0172] As the electrochemical reaction proceeds, the membrane and electrode materials will be damaged, resulting in an increase in ohmic voltage and a decrease in fuel cell performance. The formula for calculating the attenuation of membrane thickness and conductivity over operating time is as follows

[0173]

[0174] In the formula, F R is the fluoride release rate, ρ f is the fluoride content ratio of the membrane, ρ M is the film density; σ is the film thickness and conductivity;

[0175] Electronic resistance R ele As shown below:

[0176] R ele (t) = R0 + b R t (20)

[0177] Where R0 is the initial resistance value, b R is the degradation rate of the resistor material. ele (t) is the electronic resistance at time t.

[0178] Embodiment 5:

[0179] A reliability assessment method for an electric-hydrogen integrated energy system based on an aging failure model of an electric-hydrogen conversion device, the technical content of which is the same as any one of Embodiments 1-4, and further, the aging failure reliability model of the electric-hydrogen conversion device is as follows:

[0180] U=U0+U age -U0U age (twenty one)

[0181] Where U is the total unavailability rate of the equipment, and U0 is the unavailability rate of repairable failure;

[0182] Among them, the aging failure unavailability rate of hydrogen energy equipment U age As shown below:

[0183]

[0184] Where λ is the equipment aging failure rate, and μ is the equipment repair rate.

[0185] The aging failure rate λ based on the Weibull distribution is as follows:

[0186]

[0187] Wherein, E is the operating voltage of the electric-to-hydrogen conversion device, E0 is the electrochemical reaction voltage defined by Gibbs free energy inside the electric-to-hydrogen conversion device; β is the shape parameter, η is the proportional parameter, and D is the degradation rate of the operating voltage of the electric-to-hydrogen conversion device caused by membrane electrode degradation.

[0188] Embodiment 6:

[0189] A reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, the technical content of which is the same as any one of Embodiments 1-5, and further, an objective function f of an optimal load reduction model for an electric-hydrogen integrated energy system considering the aging failure of the electric-hydrogen conversion equipment is as follows:

[0190]

[0191] In the formula, c DG is the unit penalty cost for abandoning wind and solar power; Ω WG ,Ω PV are the grid-connected node sets of wind and solar generators respectively; ΔP WG,it , ΔP PV,it are the abandoned wind and solar power respectively; T is the dispatching period; n is the number of nodes; Z is the set of load types supplied by the electric-hydrogen integrated energy system, including electric and hydrogen loads; c z The penalty cost for unit reduction of the load of class z; L z,it is the power reduction of the z-th load; the subscripts i and t represent the node and time respectively. Δt is the time step.

[0192] Embodiment 7:

[0193] A reliability assessment method for an electric-hydrogen integrated energy system based on an aging failure model of electric-hydrogen conversion equipment, the technical content of which is the same as any one of Examples 1-6. Furthermore, the constraints of the optimal load reduction model of the electric-hydrogen integrated energy system considering the aging failure of the electric-hydrogen conversion equipment include proton exchange membrane fuel cell operation constraints, operation constraints on the relationship between the hydrogen consumption and output power of the fuel cell, operation constraints on the proton exchange membrane electrolyzer, operation constraints on the relationship between the hydrogen production and power consumption of the electrolyzer, electric power balance constraints, and hydrogen balance constraints.

[0194] Embodiment 8:

[0195] A reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, the technical content of which is the same as any one of Examples 1-7, and further, the proton exchange membrane fuel cell operation constraints are as follows:

[0196]

[0197] In the formula, m FC,t is the hydrogen consumption of the fuel cell at time t, P FC,tis the power generated by the fuel cell at time t; N fc is the number of fuel cells connected in series and parallel; P FC,t I is the active power output of the fuel cell; fc,t is the working current of the fuel cell; k1 and k2 are conversion coefficients; F is the Faraday constant; E PEMFC,t is the output voltage of the proton exchange membrane fuel cell at time t;

[0198] The operating constraints of the fuel cell's hydrogen consumption and output power are as follows:

[0199] Q FC,it =ρ H2 m FC,it (28)

[0200] P FC,it =g(m FC,it ) (29)

[0201] μ FC,it Q FC,min ≤Q FC,it ≤μ FC,it Q FC,max (30)

[0202] In the formula, μ FC,it is the start-stop state variable of the fuel cell. If it is 1, it indicates the start state, and if it is 0, it indicates the stop state; Q FC,max , Q FC,min The hydrogen consumption of the fuel cell is Q FC,it The upper and lower limits of H2 is the standard density of hydrogen; P FC,it is the active power output of the fuel cell; m FC,it is the hydrogen consumption of the fuel cell; g(m FC,it ) is the relationship function between the active power of the fuel cell and the hydrogen consumption;

[0203] The operating constraints of the proton exchange membrane electrolyzer are as follows:

[0204] P EL,t =k1N el E PEMWE,t I el,t (31)

[0205]

[0206] Where P EL,t is the power consumption at time t, m EL,t is the hydrogen production at time t, N el is the number of electrolytic cells connected in series and parallel, P EL,it I is the active power consumed by the electrolytic cell; el,tis the working current of the electrolytic cell; E PEMWE,t is the operating voltage of the proton exchange membrane electrolyzer at time t, η f is the number of connected electrolytic cells;

[0207] The operating constraints of the electrolyzer on the relationship between hydrogen production and power consumption are as follows:

[0208]

[0209] μ EL,it P EL,min ≤P EL,it ≤μ EL,it P EL,max (34)

[0210] In the formula, ρ H2 is the standard density of hydrogen; μ EL,it is the start-stop state variable of the electrolytic cell. If it is 1, it indicates the start state, and if it is 0, it indicates the stop state; P EL,max and P EL,min The power consumption of the electrolytic cell is P EL,it The upper and lower limits of Q is the relationship between the hydrogen production and power consumption of the electrolyzer; EL,it is the hydrogen production of the electrolyzer;

[0211] The electrical power balance constraints are as follows:

[0212]

[0213] Where P GEN,it P is the active power output by the generator set; WG,it , P PV,it are the active power actually output by the wind and solar units; P FC,it , P EL,it are the active power output by the fuel cell and the active power consumed by the electrolyzer; P load,it , L p,it are the active load and load reduction power respectively; B is the node susceptance matrix used for DC power flow calculation, and θ is the node voltage phase angle.

[0214] The hydrogen balance constraints are as follows:

[0215] Q DP,in,it =Q EL,it -Q HT,in,it +Q HT,out,it -Q FC,it (36)

[0216] Q DP,out,it =Q load,it -L q,it (37)

[0217] In the formula, Q DP,in,it , Q DP,out,it are the amount of hydrogen input and output of the hydrogenation unit; Q EL,it , Q FC,it are the hydrogen production of the electrolyzer and the hydrogen consumption of the fuel cell; Q HT,in,it , Q HT,out,it are the hydrogen filling and dehydration amounts of the hydrogen storage tank respectively; Q load,it , L q,it They are the demand and reduction of hydrogen load respectively.

[0218] Embodiment 9:

[0219] A reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, the technical content of which is the same as any one of Embodiments 1-8, and further, the power supply reliability reduction rate R ESR As shown below:

[0220]

[0221] In the formula, EENS age and EENS0 are the expected energy shortage of the electric load of the electric-hydrogen integrated energy system before and after the aging and failure of the electric-hydrogen conversion equipment.

[0222] Hydrogen supply reliability reduction rate R HSR As shown below:

[0223]

[0224] Where, EHNS age and EHNS0 are the expected hydrogen load shortage energy of the electric-hydrogen integrated energy system before and after aging and failure of the electric-hydrogen conversion equipment.

[0225] Embodiment 10:

[0226] A reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, the technical content of which is the same as any one of embodiments 1-9, further, in step 5), the step of calculating the system reliability assessment index and assessing the reliability level of the electric-hydrogen integrated energy system comprises:

[0227] 5.1) Input the relevant data of the electric-hydrogen integrated energy system and equipment parameters, and initialize the operating status of all equipment;

[0228] 5.2) System operation status obtained through Monte Carlo simulation sampling;

[0229] 5.3) Initialize simulation time d = 1 and simulation years N y =1;

[0230] 5.4) Obtain the system state at the dth moment, solve the optimal load reduction model of the electric-hydrogen integrated energy system, and obtain the load reduction state and optimal load reduction amount at that moment;

[0231] 5.5) If d>8760, go to step 5.6), otherwise let d=d+1 and go to step 5.4);

[0232] 5.6) Calculate the Nth y The reliability evaluation index of aging energy supply of electric-hydrogen integrated energy system in 2018 is set as y =N y +1;

[0233] 5.7) If N y >20000 or the variance ε of the expected value of system load reduction index <0.05, go to step 5.8), otherwise set d = 1 and go to step 5.4);

[0234] 5.8) Reliability evaluation indicators of output electricity-hydrogen integrated energy system.

[0235] Embodiment 11:

[0236] A reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model comprises the following steps:

[0237] 1) Describe the electricity-hydrogen conversion and energy coupling process of the electricity-hydrogen integrated energy system, and establish the operation model of the electricity-hydrogen conversion equipment (including proton exchange membrane electrolyzer and proton exchange membrane fuel cell);

[0238] See also Figure 1 The electric-hydrogen conversion and energy coupling process of the electric-hydrogen integrated energy system includes using surplus electricity to electrolyze water to produce hydrogen to meet the hydrogen load demand when the wind and solar power output is large or the conventional power load demand is small, and the hydrogen can also be compressed into a hydrogen storage tank for storage; when the wind and solar power output is small or the conventional power load demand is large, hydrogen fuel cells are used to generate electricity to meet the power load demand.

[0239] See also Figure 2 , the operation model of the electric-hydrogen conversion device (including proton exchange membrane electrolyzer and proton exchange membrane fuel cell) is as follows:

[0240] The operation model of the electric-hydrogen conversion device (including proton exchange membrane electrolyzer and proton exchange membrane fuel cell) is as follows:

[0241] 1.1) Proton exchange membrane electrolyzer:

[0242] The actual working voltage can be expressed as the sum of the reversible voltage and the overvoltage:

[0243] E PEMWE =Erev +E act +E ohm +E con (1)

[0244] In the formula, E rev is the reversible voltage, E act 、E ohm and E con They are activation voltage, ohmic voltage and concentration voltage. The concentration voltage is relatively small and can be ignored. con =0V.

[0245] Reversible voltage E rev is the minimum voltage required for electrolysis in the electrolytic cell:

[0246] ΔG=ΔH-T·ΔS (2)

[0247]

[0248] In the formula, under standard conditions (1 atm), the temperature T is 298.15 K and the entropy ΔS is 0.1631 kJ·mol -1 K -1 , enthalpy ΔH is 285.84 kJ·mol -1 , the number of electrons transferred to generate 1 mole of hydrogen is n = 2, and the Faraday constant is F = 96485 C·mol -1 , so E rev =1.23V.

[0249] The activation voltage consists of the cathode activation voltage and the anode activation voltage:

[0250] E act =E act,a +E act,c (4)

[0251]

[0252] In the formula, gas reaction constant R = 8.314 J·K -1 ·mol -1 , the stoichiometric coefficient of water electrolysis z = 2, the charge transfer coefficient α a =α c =0.5.

[0253] The ohmic voltage is caused by the equivalent resistance inside the electrolytic cell, which is composed of the voltage of the membrane resistance and the voltage of the electronic resistance:

[0254] E ohm =E ohm,mem +E ohm,ele =R mem ·i0+R ele·i0 (6)

[0255] in,

[0256]

[0257] τ=0.08533T-6.77632

[0258] In the formula, is the membrane thickness, σ is the conductivity of the membrane, and τ is the humidification degree (water content) of the membrane.

[0259] 1.2) Proton exchange membrane fuel cell:

[0260] Due to the activation polarization loss (E act ), Ohmic polarization loss (E ohm ) and concentration polarization loss (E conc ), the actual output voltage is expressed as:

[0261] E PEMFC =E rev -E act -E ohm -E conc (8)

[0262] The concentration polarization loss is relatively small and can be ignored. conc ≈0V.

[0263] Reversible voltage E rev is the theoretical maximum operating voltage for power generation within a fuel cell:

[0264] ΔG=ΔH-T·ΔS (9)

[0265]

[0266] In the formula, under standard conditions (1 atm), the temperature T is 298.15 K and the entropy ΔS is 0.1631 kJ·mol -1 K -1 , enthalpy ΔH is 285.84 kJ·mol -1 , the number of electrons transferred to generate 1 mole of hydrogen is n = 2, and the Faraday constant is F = 96485 C·mol -1 , so E rev =1.23V.

[0267] The activation polarization loss voltage consists of the cathode activation polarization loss voltage and the anode activation polarization loss voltage:

[0268] E act =E act,a +E act,c (11)

[0269]

[0270] In the formula, gas reaction constant R = 8.314 J·K -1 ·mol -1 , the stoichiometric coefficient of water electrolysis z = 2, the charge transfer coefficient α a =α c =0.5.

[0271] The ohmic voltage is caused by the equivalent resistance inside the fuel cell, which is composed of the voltage of the membrane resistance and the voltage of the electronic resistance:

[0272] E ohm =E ohm,mem +E ohm,ele =R mem ·i0+R ele ·i0 (13)

[0273] in,

[0274]

[0275] τ=0.08533T-6.77632

[0276] In the formula, is the membrane thickness, σ is the conductivity of the membrane, and τ is the humidification degree (water content) of the membrane.

[0277] 2) Establish an aging failure reliability model for electric-hydrogen conversion equipment considering membrane electrode degradation;

[0278] The reliability model of aging failure of the electric-hydrogen conversion equipment considering membrane electrode degradation is as follows:

[0279]

[0280] In the formula, F R is the fluoride release rate, ρ f is the fluoride content ratio of the membrane, ρ M is the film density.

[0281] The calculation formula for the resistance change caused by the loss of electronic materials such as electrodes is as follows:

[0282] R ele (t) = R0 + b R t (17)

[0283] Where R0 is the initial resistance value, b R is the degradation rate of the resistor material.

[0284] After degradation, the voltage change rate reflecting the performance of the device is defined as follows:

[0285]

[0286] Wherein, E is the operating voltage of the electric-hydrogen conversion device, and E0 is the electrochemical reaction voltage defined by Gibbs free energy inside the electric-hydrogen conversion device.

[0287] The voltage degradation state of the equipment is used to establish an aging failure rate model based on Weibull distribution:

[0288]

[0289] The aging failure unavailability rate of hydrogen energy equipment is:

[0290]

[0291] Considering the union of the repairable failure unavailability rate and the aging failure unavailability rate, the total equipment unavailability rate is calculated:

[0292] U=U0+U age -U0U age (twenty one)

[0293] Where U is the total unavailability rate of the equipment, and U0 is the unavailability rate of repairable failure.

[0294] 3) Construct an optimal load reduction model for the electric-hydrogen integrated energy system taking into account the aging and failure of electric-hydrogen conversion equipment;

[0295] The optimal load reduction model of the electric-hydrogen integrated energy system considering the aging and failure of the electric-hydrogen conversion equipment is as follows:

[0296] The objective function is to minimize the sum of the penalty costs for abandoning wind and solar power and the penalty costs for reducing electric and hydrogen loads.

[0297]

[0298] In the formula, c DG is the unit penalty cost for abandoning wind and solar power; Ω WG ,Ω PV are the grid-connected node sets of wind and solar generators respectively; ΔP WG,it , ΔP PV,it are the abandoned wind and solar power respectively; T is the dispatching period; n is the number of nodes; Z is the set of load types supplied by the electric-hydrogen integrated energy system, including electric and hydrogen loads; c z The penalty cost for unit reduction of the load of class z; L z,it is the power reduction of the z-th load. The subscripts i and t represent the node i and time t respectively.

[0299] Operation constraints of electric-to-hydrogen conversion equipment considering membrane electrode degradation:

[0300] 3.1) Proton Exchange Membrane Fuel Cell

[0301]

[0302] In the formula, m FC,t (Nm 3 ) is the hydrogen consumption of the fuel cell at time t, P FC,t (kW) is the power generated by the fuel cell at time t N fc is the number of fuel cells connected in series and parallel, P FC,t is the active power output of the fuel cell, I fc,t is the working current of the fuel cell, k1 and k2 are conversion coefficients.

[0303] The operating constraints of the fuel cell's hydrogen consumption and output power are as follows:

[0304] Q FC,it =ρ H2 m FC,it (25)

[0305] P FC,it =g(m FC,it ) (26)

[0306] μ FC,it Q FC,min ≤Q FC,it ≤μ FC,it Q FC,max (27)

[0307] In the formula, μ FC,it is the start-stop state variable of the fuel cell. If it is 1, it indicates the start state, and if it is 0, it indicates the stop state; Q FC,max , Q FC,min are the upper and lower limits of fuel cell hydrogen consumption, ρ H2 is the standard density of hydrogen (kg / Nm 3 ).

[0308] 3.2) Proton exchange membrane electrolyzer

[0309] P EL,t =k1N el E PEMWE,t I el,t (28)

[0310]

[0311] Where P EL,t (kW) is the power consumption at time t, m EL,t (Nm 3 ) is the hydrogen production at time t, N el is the number of electrolytic cells connected in series and parallel, P EL,itis the active power consumed by the electrolytic cell.

[0312] The operating constraints of the electrolyzer on the relationship between hydrogen production and power consumption are as follows:

[0313]

[0314] μ EL,it P EL,min ≤P EL,it ≤μ EL,it P EL,max (31)

[0315] In the formula, ρ H2 is the standard density of hydrogen (kg / Nm 3 ); μ EL,it is the start-stop state variable of the electrolytic cell. If it is 1, it indicates the start state, and if it is 0, it indicates the stop state; P EL,max and P EL,min They are the upper and lower limits of the electrolytic cell power consumption respectively.

[0316] 3.3) Electric power balance constraints:

[0317]

[0318] Where P GEN,it P is the active power output by the generator set; WG,it , P PV,it are the active power actually output by the wind and solar units; P FC,it , P EL,it are the active power output by the fuel cell and the active power consumed by the electrolyzer; P load,it , L p,it are the active load and load reduction power respectively; B is the node susceptance matrix used for DC power flow calculation, and θ is the node voltage phase angle.

[0319] 3.4) Hydrogen balance constraints:

[0320] Q DP,in,it =Q EL,it -Q HT,in,it +Q HT,out,it -Q FC,it (33)

[0321] Q DP,out,it =Q load,it -L q,it (34)

[0322] In the formula, Q DP,in,it , Q DP,out,it are the amount of hydrogen input and output of the hydrogenation unit; Q EL,it , Q FC,itare the hydrogen production of the electrolyzer and the hydrogen consumption of the fuel cell; Q HT,in,it , Q HT,out,it are the hydrogen filling and dehydration amounts of the hydrogen storage tank respectively; Q load,it , L q,it They are the demand and reduction of hydrogen load respectively.

[0323] 4) Construct the reliability evaluation index of power supply reliability reduction rate and hydrogen supply reliability reduction rate for aging energy supply of electric-hydrogen integrated energy system;

[0324] The evaluation index of aging energy supply reliability of the power supply reliability reduction rate and hydrogen supply reliability reduction rate of the electric-hydrogen integrated energy system is as follows:

[0325] 4.1) Reduction Rate of Electricity Supply Reliability, R ESR )

[0326]

[0327] In the formula, EENS age and EENS0 are the expected energy shortage of the electric load of the electric-hydrogen integrated energy system before and after the aging and failure of the electric-hydrogen conversion equipment.

[0328] 4.2) Reduction Rate of Hydrogen Supply Reliability (R HSR )

[0329]

[0330] Where, EHNS age and EHNS0 are the expected hydrogen load shortage energy of the electric-hydrogen integrated energy system before and after aging and failure of the electric-hydrogen conversion equipment.

[0331] 5) Solve the optimal load reduction model under all system operating conditions, calculate the system reliability evaluation index, and evaluate the reliability level of the electric-hydrogen integrated energy system.

[0332] See also Figure 3 , solving the optimal load reduction model under all system operating conditions, calculating the system reliability evaluation index, and evaluating the reliability level of the electric-hydrogen integrated energy system include:

[0333] 5.1) Input the relevant data of the electric-hydrogen integrated energy system and its equipment parameters, and initialize the operating status of all equipment;

[0334] 5.2) System operation status obtained through Monte Carlo simulation sampling;

[0335] 5.3) Initialize simulation time d = 1 and simulation years N y =1;

[0336] 5.4) Obtain the system state at the dth moment, solve the optimal load reduction problem of the system at that moment, and obtain the load reduction state and optimal load reduction amount at that moment;

[0337] 5.5) If d>8760, go to step 6), otherwise let d=d+1 and go to step 4);

[0338] 5.6) Calculate the Nth y The system reliability evaluation index of the year, and let N y =N y +1;

[0339] 5.7) If N y >20000 or the variance ε of the expected value of system load reduction index <0.05, go to step 8), otherwise set d = 1 and go to step 4);

[0340] 5.8) Reliability evaluation indicators of output electricity-hydrogen integrated energy system.

[0341] Embodiment 12:

[0342] A simulation example to verify the reliability assessment method of the electric-hydrogen integrated energy system based on the aging failure model of the electric-hydrogen conversion equipment is taken as the basis of the IEEE-RTS79 system, and the electric-hydrogen integrated energy system composed of the hydrogen energy system configured at nodes 5, 8, 17, 18, and 20 is used as an example to prove the feasibility and effectiveness of the reliability model of the electric-hydrogen conversion equipment aging failure model and the reliability assessment method of the electric-hydrogen integrated energy system. Using the traditional two-state reliability assessment model and the reliability assessment model considering the aging of the electric-hydrogen conversion equipment, the energy supply reliability indicators of the electric-hydrogen integrated energy system are compared and analyzed.

[0343] Scenario 1: Use the traditional two-state reliability assessment model to evaluate the energy supply reliability indicators of the electric-hydrogen integrated energy system.

[0344] Scenario 2: The electric-hydrogen conversion equipment adopts the electric-hydrogen conversion equipment aging failure model proposed in this article, and other equipment adopts the traditional two-state reliability assessment model to evaluate the energy supply reliability indicators of the electric-hydrogen integrated energy system.

[0345] By solving and simulating the model, the reliability index of the electric-hydrogen integrated energy system is calculated year by year within 10 years of operation, such as Figure 4a) to d). LOELP and EENS are the reduction probability, reduction time expectation and shortage energy expectation of electric load, respectively; LOHLP and EHNS are the reduction probability, reduction time expectation and shortage energy expectation of hydrogen load, respectively. As can be seen from the results in the figure, with the increase of commissioning time, the aging and failure of the electric-hydrogen conversion equipment will have a certain impact on the system energy supply reliability. In order to accurately evaluate the system reliability level, the aging effect of the electric-hydrogen conversion equipment over the commissioning time cannot be ignored.

[0346] The annual power supply reliability reduction rate and hydrogen supply reliability reduction rate calculated within 10 years of operation of the electric-hydrogen integrated energy system are shown in Table 1. The aging and failure of the electric-hydrogen conversion equipment has no significant effect on the reliability index of the electric load reduction, but has a very significant impact on the reliability index of the hydrogen load reduction, showing an increasing trend year by year. This is because as the operating time of the electric-hydrogen conversion equipment increases, its aging and failure leads to an increase in the unavailability rate of the equipment, resulting in insufficient hydrogen production capacity of the hydrogen energy system, thereby increasing the hydrogen load reduction index. In addition, the hydrogen supply reliability reduction rate (i.e., the rate of change of the expected hydrogen deficiency energy) shows a trend of increasing year by year, especially in the later stage of equipment use, the impact of aging and failure on the system reliability index is more significant. It can be seen that when evaluating the energy supply reliability of the electric-hydrogen integrated energy system, it is necessary to consider the impact of aging and failure of electric-hydrogen conversion equipment.

[0347] Table 1 System energy supply reliability evaluation results in different scenarios

[0348]

[0349]

Claims

1. A reliability assessment method for an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model, characterized in that: The following steps are involved: 1) Based on the electricity-hydrogen conversion and energy coupling process of the electricity-hydrogen integrated energy system, an operation model of the electricity-hydrogen conversion equipment is established. 2) Establish an aging failure reliability model for electric-hydrogen conversion equipment considering membrane electrode degradation; 3) Construct an optimal load reduction model for the electric-hydrogen integrated energy system considering the aging and failure of electric-hydrogen conversion equipment; 4) Construct the expressions of power supply reliability reduction rate and hydrogen supply reliability reduction rate as the evaluation indicators of aging energy supply reliability of the electric-hydrogen integrated energy system; 5) Solve the optimal load reduction model under all system operating conditions, calculate the system reliability evaluation index, and evaluate the reliability level of the electric-hydrogen integrated energy system.

2. The reliability assessment method of an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model according to claim 1 is characterized in that: The electric-hydrogen conversion equipment operation model includes a proton exchange membrane electrolyzer operation model and a proton exchange membrane fuel cell operation model.

3. The reliability assessment method of an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model according to claim 2 is characterized in that: The operation model of the proton exchange membrane electrolyzer is as follows: AND PEMWE =And rev +E act +E ohm (1) In the formula, E rev is the reversible voltage, E act 、E ohm They are activation voltage, ohmic voltage and E PEMWE is the operating voltage of the proton exchange membrane electrolyzer; Among them, the reversible voltage E rev As shown below: ΔG=ΔH-T·ΔS (2) In the formula, T is temperature; ΔS is entropy, ΔH is enthalpy; n is the number of electrons transferred to generate 1 mole of hydrogen; F is the Faraday constant; ΔG is the intermediate parameter; Activation voltage E act As shown below: AND act =And act,a +E act,c (4) Where R is the gas reaction constant; z is the stoichiometric coefficient of water electrolysis; α a , α c is the charge transfer coefficient; i a 、i c is the anode current and cathode current of the electrolytic cell; E act,a 、E act,c are the anode voltage and cathode voltage of the electrolytic cell; i 0,a 、i 0,c are the anode initial current and cathode initial current of the electrolytic cell; Ohm voltage E ohm As shown below: AND ohm =And ohm,mem +E ohm,ele =R mem i0+R ele ·i0 (6) In the formula, E ohm,mem 、E ohm,ele is the voltage of the membrane resistor and the voltage of the electronic resistor; i0 is the current; R mem , R ele It is the membrane resistance and electronic resistance; Membrane resistance R mem As shown below: τ=0.08533T-6.77632 In the formula, is the initial thickness of the membrane, σ0 is the initial conductivity of the membrane, and τ is the humidification degree of the membrane; The calculation formula for the attenuation of membrane thickness and conductivity over operating time is as follows: In the formula, F R is the fluoride release rate, ρ f is the fluoride content ratio of the membrane, ρ M is the film density; t is the time; σ is the film thickness and conductivity; The resistance change caused by the loss of electronic materials is calculated as follows R ele (t)=R0+b R t (10) Where R0 is the initial resistance value, b R is the degradation rate of the resistor material; R ele (t) is the electronic resistance at time t.

4. The reliability assessment method of an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model according to claim 2 is characterized in that: The operation model of proton exchange membrane fuel cell is as follows: AND PEMFC =And rev -AND act -AND ohm (11) In the formula, E act 、E ohm is the activation polarization loss and ohmic polarization loss; E rev is the reversible voltage; E PEMFC Output voltage for proton exchange membrane fuel cell; Among them, the reversible voltage E rev As shown below: ΔG=ΔH-T·ΔS (12) In the formula, T is temperature; ΔS is entropy, ΔH is enthalpy; n is the number of electrons transferred to generate 1 mole of hydrogen; F is the Faraday constant; ΔG is the intermediate parameter; Activation polarization loss E act As shown below: Where R is the gas reaction constant; z is the stoichiometric coefficient of water electrolysis; α a , α c is the charge transfer coefficient; i a 、i c is the anode current and cathode current of the fuel cell; E act,a 、E act,c are the anode voltage and cathode voltage of the fuel cell; i 0,a 、i 0,c are the anode initial current and cathode initial current of the fuel cell; Ohmic polarization loss E ohm As shown below: AND ohm =And ohm,mem +E ohm,ele =R mem i0+R ele ·i0 (16) In the formula, E ohm,mem 、E ohm,ele is the voltage of the membrane resistor and the voltage of the electronic resistor; i0 is the current; R mem , R ele It is the membrane resistance and electronic resistance; Membrane resistance R mem As shown below: τ=0.08533T-6.77632 In the formula, is the initial thickness of the membrane, σ0 is the initial conductivity of the membrane, and τ is the humidification degree of the membrane. The calculation formula for the attenuation of membrane thickness and conductivity with operating time is as follows In the formula, F R is the fluoride release rate, ρ f is the fluoride content ratio of the membrane, ρ M is the film density; t is the time; σ is the film thickness and conductivity; Electronic resistance R ele As shown below: R ele (t)=R0+b R t (20) Where R0 is the initial resistance value, b R is the degradation rate of the resistor material; R ele (t) is the electronic resistance at time t.

5. The reliability assessment method of an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model according to claim 1 is characterized in that: The reliability model of aging failure of electric-hydrogen conversion equipment is as follows: U=U0+U age -U0U age (21) Where U is the total unavailability rate of the equipment, and U0 is the unavailability rate of repairable failure; Among them, the aging failure unavailability rate of hydrogen energy equipment U age As shown below: Where λ is the equipment aging failure rate, and μ is the equipment repair rate. The aging failure rate λ based on the Weibull distribution is as follows: Wherein, E is the operating voltage of the electric-to-hydrogen conversion device, E0 is the electrochemical reaction voltage defined by Gibbs free energy inside the electric-to-hydrogen conversion device; β is the shape parameter, η is the proportional parameter, and D is the degradation rate of the operating voltage of the electric-to-hydrogen conversion device caused by membrane electrode degradation.

6. The reliability assessment method of an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model according to claim 1 is characterized in that: The objective function f of the optimal load reduction model of the electric-hydrogen integrated energy system considering the aging and failure of the electric-hydrogen conversion equipment is as follows: In the formula, c DG is the unit penalty cost for abandoning wind and solar power; Ω WG ,Ω PV are the grid-connected node sets of wind and solar generators respectively; ΔP WG,it , ΔP PV,it are the abandoned wind and solar power respectively; T is the dispatching period; n is the number of nodes; Z is the set of load types supplied by the electric-hydrogen integrated energy system, including electric and hydrogen loads; c z The penalty cost for unit reduction of the z-th load; L z,it is the power reduction of the z-th type of load; the subscripts i and t represent the node and time respectively; Δt is the time step.

7. The reliability assessment method of an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model according to claim 1 is characterized in that: The constraints of the optimal load reduction model of the electric-hydrogen integrated energy system considering the aging and failure of the electric-hydrogen conversion equipment include the operation constraints of the proton exchange membrane fuel cell, the operation constraints of the relationship between the hydrogen consumption and output power of the fuel cell, the operation constraints of the proton exchange membrane electrolyzer, the operation constraints of the relationship between the hydrogen production and power consumption of the electrolyzer, the electric power balance constraints, and the hydrogen balance constraints.

8. The reliability assessment method of an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model according to claim 7 is characterized in that: The operating constraints of proton exchange membrane fuel cells are as follows: In the formula, m FC,t is the hydrogen consumption of the fuel cell at time t, P FC,t is the power generated by the fuel cell at time t; N fc is the number of fuel cells connected in series and parallel; I fc,t is the working current of the fuel cell; k1 and k2 are conversion coefficients; F is the Faraday constant; E PEMFC,t is the output voltage of the proton exchange membrane fuel cell at time t; The operating constraints of the fuel cell's hydrogen consumption and output power are as follows: Q FC,it =ρ H2 m FC,it (28) P FC,it =g(m FC,it ) (29) μ FC,it Q FC,min ≤Q FC,it ≤μ FC,it Q FC,max (30) In the formula, μ FC,it is the start-stop state variable of the fuel cell. If it is 1, it indicates the start state, and if it is 0, it indicates the stop state; Q FC,max , Q FC,min The hydrogen consumption of the fuel cell is Q FC,it The upper and lower limits of H2 is the standard density of hydrogen; P FC,it is the active power output of the fuel cell; m FC,it is the hydrogen consumption of the fuel cell; g(m FC ,it) is the relationship function between the active power of the fuel cell and the hydrogen consumption; The operating constraints of the proton exchange membrane electrolyzer are as follows: P EL,t =k1N el E PEMWE,t IN el,t (31) Where P EL,t is the power consumption at time t, m EL,t is the hydrogen production at time t, N el is the number of electrolytic cells connected in series and parallel, P EL,it I is the active power consumed by the electrolytic cell; el,t is the working current of the electrolytic cell; E PEMWE,t is the operating voltage of the proton exchange membrane electrolyzer at time t, η f is the number of connected electrolytic cells; The operating constraints of the electrolyzer on the relationship between hydrogen production and power consumption are as follows: μ EL,it P EL,min ≤P EL,it ≤μ EL,it P EL,max (34) In the formula, ρ H2 is the standard density of hydrogen; μ EL,it is the start-stop state variable of the electrolytic cell. If it is 1, it indicates the start state, and if it is 0, it indicates the stop state; P EL,max and P EL,min The power consumption of the electrolytic cell is P EL,it The upper and lower limits of f sEL,it (P EL,it ) is the relationship between the hydrogen production and power consumption of the electrolyzer; Q EL,it is the hydrogen production of the electrolyzer; The electrical power balance constraints are as follows: Where P GEN,it P is the active power output by the generator set; WG,it , P PV,it are the active power actually output by the wind and solar units; P FC,it , P EL,it are the active power output by the fuel cell and the active power consumed by the electrolyzer; P load,it , L p,it are the active load and load reduction power respectively; B is the node susceptance matrix used for DC power flow calculation, and θ is the node voltage phase angle. The hydrogen balance constraints are as follows: Q DP,in,it =Q EL,it -Q HT,in,it +Q HT,out,it -Q FC,it (36) Q DP,out,it =Q load,it -L q,it (37) In the formula, Q DP,in,it , Q DP,out,it are the amount of hydrogen input and output of the hydrogenation unit; Q EL,it , Q FC,it are the hydrogen production of the electrolyzer and the hydrogen consumption of the fuel cell; Q HT,in,it , Q HT,out,it are the hydrogen filling and dehydration amounts of the hydrogen storage tank respectively; Q load,it , L q,it They are the demand and reduction of hydrogen load respectively.

9. The reliability assessment method of an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model according to claim 1 is characterized in that: Power supply reliability reduction rate R ESR As shown below: In the formula, EENS age and EENS0 are the expected energy shortage of electric load in the electric-hydrogen integrated energy system before and after aging and failure of the electric-hydrogen conversion equipment. Hydrogen supply reliability reduction rate R HSR As shown below: Where, EHNS age and EHNS0 are the expected hydrogen load shortage energy of the electric-hydrogen integrated energy system before and after aging and failure of the electric-hydrogen conversion equipment.

10. The reliability assessment method of an electric-hydrogen integrated energy system based on an electric-hydrogen conversion equipment aging failure model according to claim 1 is characterized in that: In step 5), the steps of calculating the system reliability evaluation index and evaluating the reliability level of the electric-hydrogen integrated energy system include: 5.1) Input the relevant data of the electric-hydrogen integrated energy system and equipment parameters, and initialize the operating status of all equipment; 5.2) System operation status obtained through Monte Carlo simulation sampling; 5.3) Initialize simulation time d = 1 and simulation years N y =1; 5.4) Obtain the system state at the dth moment, solve the optimal load reduction model of the electric-hydrogen integrated energy system, and obtain the load reduction state and optimal load reduction amount at that moment; 5.5) If d>8760, go to step 5.6), otherwise let d=d+1 and go to step 5.4); 5.6) Calculate the Nth y The reliability evaluation index of aging energy supply of electric-hydrogen integrated energy system in 2018 is set as y =N y +1; 5.7) If N y >20000 or the variance ε of the expected value of system load reduction index <0.05, go to step 5.8), otherwise set d = 1 and go to step 5.4); 5.8) Reliability evaluation indicators of output electricity-hydrogen integrated energy system.

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