User-side-oriented photovoltaic energy storage system capacity configuration method

Abstract

The invention discloses a user-side-oriented photovoltaic energy storage system capacity configuration method, which comprises the following steps of: firstly, constructing a photovoltaic output model based on photovoltaic equipment, then calculating annual total income and the cost of a photovoltaic energy storage system, establishing operation constraint conditions of the photovoltaic equipment and the energy storage equipment, and finally modeling a target to obtain a target function and solving the target function. And the photovoltaic equipment capacity cpv and the energy storage equipment capacity cbat which enable the economical efficiency to be optimal are obtained. According to the method, the full life cycle and the time-of-use electricity price are considered, so that the maximum benefit of the system is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy system capacity configuration, and more specifically, relates to a method for configuring the capacity of a photovoltaic energy storage system for a user. Background Art

[0002] In recent years, global temperatures have gradually risen. In order to cope with the increasingly severe climate crisis, countries around the world are actively developing clean energy systems based on new energy and reducing dependence on fossil energy. Among them, photovoltaic energy storage systems that use sustainable energy as the main energy supply play an important role in the low-carbon energy transition.

[0003] The photovoltaic energy storage system facing the user side is a small and medium-sized energy conversion and utilization system that can meet the regional electricity demand and can produce and supply electricity on site. The vigorous development of photovoltaic energy storage systems will help improve energy utilization and solve environmental pollution problems. At present, in order to overcome the uncertainty and volatility of photovoltaic power generation and fully grasp the time-of-use electricity price policy, corresponding energy storage will be configured for new photovoltaics. When facing the power station side, the energy storage capacity that makes the system economically optimal is generally determined on the basis of the known photovoltaic configuration capacity, but when facing the user side, only the user's electricity load is known, and it is necessary to simultaneously determine the photovoltaic capacity and energy storage capacity that make the system economically optimal. Therefore, how to scientifically coordinate the configuration of photovoltaic and energy storage capacity has become an urgent problem to be solved.

[0004] At the same time, it is necessary to analyze the economic feasibility of the photovoltaic energy storage system. The full life cycle theory is to start from the long-term benefits, consider all aspects of the project life cycle, and conduct a full-cycle benefit and cost analysis. This theory takes the time value of money into consideration and uses the net present value as a judgment standard to obtain a more realistic profit and loss situation and provide effective decision-making guidance for enterprises. In recent years, relevant central departments have proposed to implement full-process and all-round management at the beginning of the project. Therefore, it is necessary to apply the full life cycle theory to the construction process of the photovoltaic energy storage system in order to obtain the photovoltaic and energy storage capacity that optimizes the economy.

[0005] Many studies have been conducted on the capacity configuration of photovoltaic energy storage systems. However, many studies have not taken into account the factors of the entire life cycle and time-of-use electricity prices at the same time, as well as the need for coordinated configuration of photovoltaic and energy storage capacities. Therefore, there are still some shortcomings that need to be addressed. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for configuring the capacity of a photovoltaic energy storage system for a user side, taking into account the full life cycle and time-of-use electricity prices to achieve the maximum benefit of the system.

[0007] To achieve the above-mentioned object of the invention, the present invention provides a method for configuring the capacity of a photovoltaic energy storage system on the user side, which is characterized by comprising the following steps:

[0008] (1) Construct a photovoltaic output model based on photovoltaic equipment capacity:

[0009] P i (t) = α·c pv ·pv(t)·(1-δ pv ) i-1 ,1≤i≤T pv (1)

[0010] Among them, P i (t) is the output power of the photovoltaic device at the tth hour in the i-th year, α is the efficiency coefficient, c pv is the capacity of the photovoltaic equipment, pv(t) is the output power of the photovoltaic unit capacity in the tth hour under the standard experimental scenario, δ pv is the attenuation coefficient of the photovoltaic equipment output, i is the service life of the photovoltaic equipment, T pv is the life of the photovoltaic equipment;

[0011] (2) Analyze the benefits of the photovoltaic energy storage system and calculate the total annual benefits:

[0012]

[0013] Among them, C r,i is the total revenue of the photovoltaic energy storage system in year i, C pv,i is the residual value benefit brought by the replacement of photovoltaic equipment in the i-th year; C ess,i is the residual value benefit brought by the replacement of energy storage equipment in the i-th year, P tr,i (t) is the amount of electricity output from the photovoltaic energy storage system to the user at the tth hour in the i-th year, P se,i (t) is the amount of electricity output from the photovoltaic energy storage system to the grid at hour t in year i, π r,i (t) is the electricity price at the tth hour in the i-th year, π f,i (t) is the Internet access price at the tth hour in the i-th year, t is the hour number of the year, and 8760 is the number of hours in a year;

[0014] (3) Cost analysis of photovoltaic energy storage systems, including initial investment costs and operating investment costs

[0015] The cost of a photovoltaic energy storage system is divided into two parts: initial investment cost and annual operating investment cost. The initial investment cost is expressed as:

[0016] CO cs =CO tj +CO pv,c +CO ess,c (3)

[0017] Among them, CO cs is the initial investment cost, CO tj is the civil construction cost, CO pv,c is the initial purchase cost of photovoltaic equipment, CO ess,c It is the initial purchase cost of the energy storage equipment;

[0018] The annual operating investment cost is expressed as:

[0019]

[0020] Among them, C st,i is the operating investment cost of the photovoltaic energy storage system in the i-th year, C op,i is the operation and maintenance cost of the photovoltaic energy storage system in the i-th year, CO pvo,i is the replacement cost of the photovoltaic equipment in the operation period in the i-th year, CO esso,i is the replacement cost of the energy storage equipment in the operation period in the i-th year, C tax,i is the tax that the enterprise needs to pay in year i, P buy,i (t) is the amount of electricity purchased from the grid by the photovoltaic energy storage system at the tth hour in the i-th year;

[0021] (4) Analyze the operating constraints of the photovoltaic energy storage system

[0022] The operation of photovoltaic equipment in the photovoltaic energy storage system meets the following constraints:

[0023] c pv,min ≤c pv ≤c pv,max (5)

[0024] P i (t) = P 1,i (t)+P 2,i (t)+P se,i (t) (6)

[0025] Among them, c pv,min is the lower limit of the photovoltaic equipment capacity, c pv,max is the upper limit of the photovoltaic equipment capacity, P 1,i (t) is the amount of electricity provided by the photovoltaic equipment to the user at the tth hour in the i-th year, P 2,i (t) is the amount of electricity provided by the photovoltaic device to the energy storage device at the tth hour in the i-th year;

[0026] The operation of energy storage equipment in the photovoltaic energy storage system meets the following constraints:

[0027] c bat,min ≤c bat ≤c bat,max (7)

[0028] P c,i (t) = P 2,i (t)+P buy,i (t) (8)

[0029] 0≤P 1,i (t)+P d,i (t) = P tr,i (t)≤P L,i (t) (9)

[0030] Among them, c bat is the capacity of energy storage equipment, c bat,min is the lower limit of the energy storage device capacity, c bat,max is the upper limit of the energy storage device capacity, P c,i (t) is the charging capacity of the energy storage device at the tth hour in the i-th year, P d,i (t) is the discharge capacity of the energy storage device at the tth hour in the i-th year, P L,i (t) User load at hour t in year i;

[0031] The charging and discharging power of the energy storage device will be subject to the capacity of the energy storage device. The relationship between the two satisfies:

[0032]

[0033] The storage capacity of the energy storage device meets the following constraints:

[0034] ess i (1) = 0.1·c bat (11)

[0035] ess i (t+1)=ess(t)+P c,i (t)·η c -P d,i (t) / η d (12)

[0036] soc min ·c bat ≤ess i (t)≤soc max ·c bat (13)

[0037] 0≤soc min ≤1 (14)

[0038] 0≤soc max ≤1 (15)

[0039] Among them, ess i (1) is the initial storage capacity of the energy storage device, ess i(t) is the storage capacity of the energy storage device at the tth hour in the i-th year, ess i (t+1) is the storage capacity of the energy storage device at the tth hour in the i-th year, η c is the charging efficiency of the energy storage device, η d is the discharge efficiency of the energy storage device, soc min is the minimum state of charge of the energy storage device, soc max is the maximum state of charge of the energy storage device;

[0040] (5) Set the objective function for the photovoltaic energy storage system and solve it to obtain the photovoltaic equipment capacity c with the best economic efficiency. pv and the capacity of the energy storage device c bat

[0041] Based on the full life cycle theory, the time value of benefits and costs is considered, and the model is built with the goal of maximizing the net present value of the photovoltaic storage system. The objective function is:

[0042]

[0043] Where NPV is the net present value of the photovoltaic energy storage system, Max{·} is the maximum value of the formula in the brackets, N is the number of years in the project cycle, and r is the discount rate;

[0044] By solving the objective function, we can obtain the photovoltaic equipment capacity c that makes the economy optimal. pv and the capacity of the energy storage device c bat .

[0045] The object of the invention of the present invention is achieved in this way:

[0046] The capacity configuration method of the photovoltaic energy storage system for the user side of the present invention first constructs a photovoltaic output model based on photovoltaic equipment, then calculates the annual total income and the cost of the photovoltaic energy storage system and establishes the operating constraints of the photovoltaic equipment and the energy storage equipment, and finally models the target, obtains the objective function and solves it to obtain the photovoltaic equipment capacity c that makes the economy optimal. pv and the capacity of the energy storage device c bat The present invention takes into account the whole life cycle and time-of-use electricity price to achieve the maximum benefit of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a flowchart of a specific implementation method of the photovoltaic energy storage system capacity configuration method for the user side of the present invention;

[0048] Figure 2 It is the structural diagram of the photovoltaic energy storage system;

[0049] Figure 3These are the results of photovoltaic equipment configuration capacity, energy storage equipment configuration capacity and net present value under three conditions. DETAILED DESCRIPTION

[0050] The specific implementation of the present invention is described below in conjunction with the accompanying drawings so that those skilled in the art can better understand the present invention. It should be noted that in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

[0051] Example

[0052] Figure 1 It is a flowchart of a specific implementation method of the photovoltaic energy storage system capacity configuration method for the user side of the present invention;

[0053] In this embodiment, if Figure 1 As shown, the method for configuring the capacity of a photovoltaic energy storage system on the user side of the present invention comprises the following steps:

[0054] Step S1: Constructing a photovoltaic output model based on photovoltaic equipment capacity

[0055] Photovoltaic output is affected by factors such as photovoltaic installed capacity, light intensity, temperature, and the performance parameters of photovoltaic modules themselves. The photovoltaic output model is as follows:

[0056] P i (t) = α·c pv ·pv(t)·(1-δ pv ) i-1 ,1≤i≤T pv (1)

[0057] Among them, P i (t) is the output power of the photovoltaic device at the tth hour in the i-th year, α is the efficiency coefficient, c pv is the capacity of the photovoltaic equipment, pv(t) is the output power of the photovoltaic unit capacity in the tth hour under the standard experimental scenario, δ pv is the attenuation coefficient of the photovoltaic equipment output, i is the service life of the photovoltaic equipment, T pv is the life of the photovoltaic equipment.

[0058] In the present invention, the output power pv(t) is related to light intensity and temperature.

[0059] Step S2: Analyze the benefits of the photovoltaic energy storage system and calculate the total benefits for one year

[0060] The benefits of photovoltaic energy storage systems are analyzed based on the full life cycle theory. The benefits of photovoltaic energy storage systems come from three aspects: 1) the benefits of selling electricity to users; 2) the benefits of selling electricity to the power grid; 3) the benefits of equipment residual value. Equipment residual value refers to the remaining value after the photovoltaic equipment or energy storage is scrapped. The total benefits for one year are:

[0061]

[0062] In this embodiment:

[0063] C pv,i =0.05·CO pv,i

[0064] C ess,i =0.1·CO ess,i

[0065] CO pv,i =r pv,i ·c pv,i

[0066] CO ess,i =r bat,i ·c bat,i

[0067] Among them, C r,i is the total revenue of the photovoltaic energy storage system in year i, C pv,i is the residual value benefit brought by the replacement of photovoltaic equipment in the i-th year; C ess,i is the residual value benefit brought by the replacement of energy storage equipment in the i-th year, P tr,i (t) is the amount of electricity output from the photovoltaic energy storage system to the user at the tth hour in the i-th year, P se,i (t) is the amount of electricity output from the photovoltaic energy storage system to the grid at hour t in year i, π r,i (t) is the electricity price at the tth hour in the i-th year, π f,i (t) is the Internet access price at the tth hour in the i-th year, t is the hour number of the year, 8760 is the number of hours in a year, CO pv,i is the purchase cost of the photovoltaic equipment replaced in year i, CO ess,i is the purchase cost of the energy storage equipment replaced in year i, r pv,i is the unit capacity price of photovoltaic equipment in year i, c pv,i is the capacity of the photovoltaic equipment replaced in year i, r bat,i is the unit capacity price of energy storage equipment in year i, c bat,i Represents the energy storage capacity of the energy storage equipment replaced in the i-th year.

[0068] Step S3: Conduct a cost analysis on the photovoltaic energy storage system and calculate the initial investment cost and operating investment cost

[0069] The cost of photovoltaic energy storage system is analyzed based on the full life cycle theory: the cost of photovoltaic energy storage system is divided into two parts: initial investment cost and operating investment cost. The initial investment cost includes civil engineering cost, initial purchase cost of photovoltaic and energy storage equipment, which can be expressed as follows:

[0070] CO cs =CO tj +CO pv,c +CO ess,c (3)

[0071] Among them, CO cs is the initial investment cost, CO tj is the civil construction cost, CO pv,c is the initial purchase cost of photovoltaic equipment, CO ess,c It is the initial purchase cost of energy storage equipment.

[0072] The operating investment cost includes the operation and maintenance cost of the photovoltaic energy storage system, the replacement cost of the photovoltaic energy storage equipment during the operation period, the taxes that the enterprise needs to pay, and the cost of the photovoltaic energy storage system purchasing electricity from the grid. The annual operating investment cost can be expressed as follows:

[0073]

[0074] Among them, C st,i is the operating investment cost of the photovoltaic energy storage system in the i-th year, C op,i is the operation and maintenance cost of the photovoltaic energy storage system in the i-th year, CO pvo,i is the replacement cost of the photovoltaic equipment in the operation period in the i-th year, CO esso,i is the replacement cost of the energy storage equipment in the operation period in the i-th year, C tax,i is the tax that the enterprise needs to pay in year i, P buy,i (t) is the amount of electricity purchased by the photovoltaic energy storage system from the grid at the tth hour in the i-th year.

[0075] Step S4: Analyze the operating constraints of the photovoltaic energy storage system

[0076] The operation of photovoltaic equipment in the photovoltaic energy storage system meets the following constraints:

[0077] c pv,min ≤c pv ≤c pv,max (5)

[0078] P i (t) = P 1,i (t)+P 2,i (t)+P se,i (t)(6)

[0079] Among them, c pv,minis the lower limit of the photovoltaic equipment capacity, c pv,max is the upper limit of the photovoltaic equipment capacity, P 1,i (t) is the amount of electricity provided by the photovoltaic equipment to the user at the tth hour in the i-th year, P 2,i (t) is the amount of electricity provided by the photovoltaic device to the energy storage device at the tth hour in the i-th year;

[0080] The operation of energy storage equipment in the photovoltaic energy storage system meets the following constraints:

[0081] c bat,min ≤c bat ≤c bat,max (7)

[0082] P c,i (t) = P 2,i (t)+P buy,i (t) (8)

[0083] 0≤P 1,i (t)+P d,i (t) = P tr,i (t)≤P L,i (t) (9)

[0084] Among them, c bat is the capacity of energy storage equipment, c bat,min is the lower limit of the energy storage device capacity, c bat,max is the upper limit of the energy storage device capacity, P c,i (t) is the charging capacity of the energy storage device at the tth hour in the i-th year, P d,i (t) is the discharge capacity of the energy storage device at the tth hour in the i-th year, P L,i (t) User load at hour t in year i.

[0085] The charging and discharging power of the energy storage device will be subject to the capacity of the energy storage device. The relationship between the two satisfies:

[0086]

[0087] The storage capacity of the energy storage device meets the following constraints:

[0088] ess i (1) = 0.1·c bat (11)

[0089] ess i (t+1)=ess(t)+P c,i (t)·η c -P d,i (t) / η d (12)

[0090] soc min·c bat ≤ess i (t)≤soc max ·c bat (13)

[0091] 0≤soc min ≤1 (14)

[0092] 0≤soc max ≤1 (15)

[0093] Among them, ess i (1) is the initial storage capacity of the energy storage device, ess i (t) is the storage capacity of the energy storage device at the tth hour in the i-th year, ess i (t+1) is the storage capacity of the energy storage device at the tth hour in the i-th year, η c is the charging efficiency of the energy storage device, η d is the discharge efficiency of the energy storage device, soc min is the minimum state of charge of the energy storage device, soc max It is the maximum state of charge of the energy storage device.

[0094] Step S5: Set the objective function for the photovoltaic energy storage system and solve it to obtain the photovoltaic equipment capacity c with the best economic efficiency. pv and the capacity of the energy storage device c bat

[0095] Based on the full life cycle theory, the time value of benefits and costs is considered, and the model is built with the goal of maximizing the net present value of the photovoltaic storage system. The objective function is:

[0096]

[0097] Where NPV is the net present value of the photovoltaic energy storage system, Max{·} is the maximum value of the formula in the brackets, N is the number of years in the project cycle, and r is the discount rate;

[0098] By solving the objective function, we can obtain the photovoltaic equipment capacity c that makes the economy optimal. pv and the capacity of the energy storage device c bat .

[0099] Example

[0100] The proposed capacity configuration model is simulated based on real data, and the optimization results are analyzed in detail. Consider a photovoltaic energy storage system located in a certain area, whose structure is shown in the figure below. Figure 2 The specific values ​​of various parameters of the photovoltaic energy storage system are shown in Table 1.

[0101]

[0102] Table 1

[0103] In Table 1, for convenience, the Internet price π f,i (t), unit capacity price of photovoltaic equipment r pv,i 、The unit capacity price of photovoltaic equipment bat,i Set as fixed price.

[0104] The electricity price is determined according to the relevant government documents. Table 2 shows the operating parameters of distributed energy and the prices are shown in Table 2. The simulation model codes are all implemented through MATLAB+YALMIP programming, and the GUROBI solver is called for solution.

[0105]

[0106] Table 2

[0107] Table 3 Optimal capacity configuration results and some economic index results. The optimal capacity configuration results and some economic index results of photovoltaic equipment and energy storage equipment are shown in Table 3.

[0108]

[0109]

[0110] Here, IRR refers to the internal rate of return, and its value is the discount rate that makes NPV equal to zero.

[0111] The sensitivity of the photovoltaic energy storage system capacity configuration model is analyzed. It is divided into the following three cases:

[0112] (1) No changes;

[0113] (2) The unit capacity price of energy storage equipment is r bat Increased to 2100CNY / KWh;

[0114] (3) Increase the peak electricity price by 0.02CNY / KWh.

[0115] Comparison of photovoltaic configuration capacity, energy storage configuration capacity and net present value under three conditions Figure 3 shown.

[0116] from Figure 3It can be seen that in case (2), the initial investment cost and operating investment cost increase due to the increase in the unit capacity price of the energy storage equipment, which directly leads to a decrease in the configuration capacity of the energy storage equipment, thereby driving a slight decrease in the configuration capacity of the photovoltaic equipment. Therefore, compared with case (1), the capacity configuration result of the photovoltaic equipment decreases by 0.16%, the capacity configuration result of the energy storage equipment decreases by 6.48%, and the net present value decreases by 1.71%; in case (3), the peak electricity price is increased, the electricity sales revenue of the photovoltaic energy storage system is increased, and the system is prompted to configure larger capacity photovoltaic equipment and energy storage equipment. Therefore, compared with case (1), the capacity configuration result of the photovoltaic equipment increases by 0.27%, the capacity configuration result of the energy storage equipment increases by 7.27%, and the net present value increases by 15.1%. In summary, the correctness and rationality of the photovoltaic energy storage system capacity configuration method proposed in the present invention are verified through the embodiments.

[0117] Although the above describes the illustrative specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A method for configuring the capacity of a photovoltaic energy storage system for a user, characterized in that: The following steps are involved: (1) Construct a photovoltaic output model based on photovoltaic equipment capacity: P i (t)=α·c pv ·pv(t)·(1-δ pv ) i-1 ,1≤i≤T pv (1) Among them, P i (t) is the output power of the photovoltaic device at the tth hour in the i-th year, α is the efficiency coefficient, c pv is the capacity of the photovoltaic equipment, pv(t) is the output power of the photovoltaic unit capacity in the tth hour under the standard experimental scenario, δ pv is the attenuation coefficient of the photovoltaic equipment output, i is the service life of the photovoltaic equipment, T pv is the life of the photovoltaic equipment; (2) Analyze the benefits of the photovoltaic energy storage system and calculate the total annual benefits: Among them, C r,i is the total revenue of the photovoltaic energy storage system in year i, C pv,i is the residual value benefit brought by the replacement of photovoltaic equipment in the i-th year; C ess,i is the residual value benefit brought by the replacement of energy storage equipment in the i-th year, P tr,i (t) is the amount of electricity output from the photovoltaic energy storage system to the user at the tth hour in the i-th year, P se,i (t) is the amount of electricity output from the photovoltaic energy storage system to the grid at hour t in year i, π r,i (t) is the electricity price at the tth hour in the i-th year, π f,i (t) is the Internet access price at the tth hour in the i-th year, t is the hour number of the year, and 8760 is the number of hours in a year; (3) Cost analysis of photovoltaic energy storage systems, including initial investment costs and operating investment costs The cost of a photovoltaic energy storage system is divided into two parts: initial investment cost and annual operating investment cost. The initial investment cost is expressed as: WHAT cs =WHAT tj +WHAT pv,c +WHAT ess,c (3) Among them, CO cs is the initial investment cost, CO tj is the construction cost, CO pv,c is the initial purchase cost of photovoltaic equipment, CO ess,c It is the initial purchase cost of the energy storage equipment; The annual operating investment cost is expressed as: Among them, C st,i is the operating investment cost of the photovoltaic energy storage system in the i-th year, C op,i is the operation and maintenance cost of the photovoltaic energy storage system in the i-th year, CO pvo,i is the replacement cost of the photovoltaic equipment in the operation period in the i-th year, CO esso,i is the replacement cost of the energy storage equipment in the operation period in the i-th year, C tax,i is the tax that the enterprise needs to pay in year i, P buy,i (t) is the amount of electricity purchased from the grid by the photovoltaic energy storage system at the tth hour in the i-th year; (4) Analyze the operating constraints of the photovoltaic energy storage system The operation of photovoltaic equipment in the photovoltaic energy storage system meets the following constraints: c pv,min ≤c pv ≤c pv,max (5)P i (t)=P 1,i (t)+P 2,i (t)+P se,i (t)(6) Among them, c pv,min is the lower limit of the photovoltaic equipment capacity, c pv,max is the upper limit of the photovoltaic equipment capacity, P 1,i (t) is the amount of electricity provided by the photovoltaic equipment to the user at the tth hour in the i-th year, P 2,i (t) is the amount of electricity provided by the photovoltaic device to the energy storage device at the tth hour in the i-th year; The operation of energy storage equipment in the photovoltaic energy storage system meets the following constraints: c bat,min ≤c bat ≤c bat,max (7)P c,i (t)=P 2,i (t)+P buy,i (t)(8)0≤P 1,i (t)+P d,i (t)=P tr,i (t)≤P L,i (t)(9) Among them, c bat is the capacity of energy storage equipment, c bat,min is the lower limit of the energy storage device capacity, c bat,max is the upper limit of the energy storage device capacity, P c,i (t) is the charging capacity of the energy storage device at the tth hour in the i-th year, P d,i (t) is the discharge capacity of the energy storage device at the tth hour in the i-th year, P L,i (t) User load at hour t in year i; The charging and discharging power of the energy storage device will be subject to the capacity of the energy storage device. The relationship between the two satisfies: The storage capacity of the energy storage device meets the following constraints: ess i (1)=0.1·c bat (11) yes i (t+1)=ess(t)+P c,i (t)·h c -P d,i (t) / h d (12) soc min ·c bat ≤ess i (t)≤soc max ·c bat (13) 0≤soc min ≤1 (14) 0≤soc max ≤1 (15) Among them, ess i (1) is the initial storage capacity of the energy storage device, ess i (t) is the storage capacity of the energy storage device at the tth hour in the i-th year, ess i (t+1) is the storage capacity of the energy storage device at the tth hour in the i-th year, η c is the charging efficiency of the energy storage device, η d is the discharge efficiency of the energy storage device, soc min is the minimum state of charge of the energy storage device, soc max is the maximum state of charge of the energy storage device; (5) Set the objective function for the photovoltaic energy storage system and solve it to obtain the photovoltaic equipment capacity c with the best economic efficiency. pv and the capacity of the energy storage device c bat Based on the full life cycle theory, the time value of benefits and costs is considered, and the model is built with the goal of maximizing the net present value of the photovoltaic storage system. The objective function is: Where NPV is the net present value of the photovoltaic energy storage system, Max{·} is the maximum value of the formula in the brackets, N is the number of years in the project cycle, and r is the discount rate; By solving the objective function, we can obtain the photovoltaic equipment capacity c that makes the economy optimal. pv and the capacity of the energy storage device c bat .

2. The method for configuring the capacity of a photovoltaic energy storage system for a user according to claim 1, characterized in that: In step (2): C pv,i =0.05 CO pv,i C ess,i =0.1 CO ess,i WHAT pv,i =r pv,i c pv,i WHAT ess,i =r bat,i c bat,i Among them: CO pv,i is the purchase cost of the photovoltaic equipment replaced in year i, CO ess,i is the purchase cost of the energy storage equipment replaced in year i, r pv,i is the unit capacity price of photovoltaic equipment in year i, c pv,i is the capacity of the photovoltaic equipment replaced in year i, r bat,i is the unit capacity price of energy storage equipment in year i, c bat,i Represents the energy storage capacity of the energy storage equipment replaced in the i-th year.

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