Energy storage value-economy comprehensive evaluation method based on system dynamics

Abstract

The invention discloses an energy storage value-economy comprehensive evaluation method based on system dynamics, and belongs to the technical field of energy storage system dynamics value chains, and the method comprises the steps: 1, determining a system boundary and an evaluation target; 2, establishing an economic evaluation system of the life cycle of the energy storage project; step 3, carrying out energy storage comprehensive substitution value identification and evaluation; 4, constructing an energy storage value-economy evaluation model based on a system dynamics theory; step 5, based on the results of the value evaluation and the economic evaluation, performing comprehensive evaluation, and judging whether various state variable judgment criteria exceed a threshold value T or not; and giving an evaluation conclusion through multivariable comprehensive judgment. According to the invention, by establishing the dynamic model comprising the energy storage value subsystem and the economical efficiency subsystem, unified evaluation of the value and the economical efficiency of the energy storage system in the whole life cycle is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage system dynamics value chain, and specifically relates to a comprehensive evaluation method of energy storage value-economy based on system dynamics. Background Art

[0002] At present, the high construction cost and poor investment returns of energy storage systems are key factors that restrict the further development of energy storage. How to make a reasonable evaluation of the economic feasibility of energy storage is of great practical significance. It is necessary to formulate an operation strategy based on the actual situation of electricity prices and operation requirements in the power grid to achieve the maximum profit. Existing evaluation methods mostly identify value from a single dimension, such as only focusing on delaying the investment benefits of the power grid or the value of peak and frequency regulation. There is a lack of systematic evaluation of the multiple values ​​of energy storage, and it is difficult to reflect the comprehensive contribution of energy storage to the safety, reliability, and flexibility of the power grid.

[0003] The current methods for evaluating the value of energy storage mainly focus on the following two aspects:

[0004] 1. Evaluation based on the cost-benefit method. Foreign scholars generally use cost-benefit analysis methods to evaluate the comprehensive value of energy storage projects. The Electric Power Research Institute (EPRI) of the United States has proposed a method to quantify the benefits of energy storage projects, and conducts benefit analysis from the dimensions of grid investment substitution and system operation efficiency improvement. The Australian Energy Market Operator (AEMO) has established an energy storage benefit evaluation framework, focusing on the value of energy storage in new energy consumption and grid peak regulation.

[0005] Second, evaluation based on system simulation, using power system simulation methods to evaluate the value of energy storage. Currently, the effect of energy storage on grid voltage stability has been analyzed based on the EMTP simulation platform, and the role of energy storage in improving grid power supply reliability has been verified through PowerFactory simulation. This type of method can better reflect the technical value of energy storage, but it is difficult to quantify the economic benefits.

[0006] The current analysis methods for energy storage economics are mainly in the following two aspects:

[0007] 1. Traditional financial evaluation methods. The current mainstream energy storage economic analysis methods are still based on traditional financial evaluation, such as net present value method, internal rate of return method, etc. Based on the life cycle cost theory, the economic feasibility of energy storage projects is analyzed. The investment value of energy storage projects is evaluated through the real option method, taking into account the flexibility of investment decisions.

[0008] Second, comprehensive benefit evaluation methods. Some studies have attempted to consider the technical value and economic value of energy storage. A comprehensive benefit evaluation method for energy storage projects has been proposed to convert technical indicators into economic value. A multi-dimensional benefit quantification model for energy storage has been established to realize the monetization of externalities such as social benefits and environmental benefits.

[0009] The recent issue of coordinated evaluation of energy storage value and economic efficiency. This paper uses value chain analysis and other methods to sort out the value realization path of energy storage, providing new ideas for establishing a unified evaluation framework.

[0010] Problems with existing technologies:

[0011] Existing evaluation methods mostly identify value from a single dimension, such as focusing only on delaying the investment benefits of the power grid or the value of peak and frequency regulation. They lack a systematic evaluation of the multiple values ​​of energy storage and are unable to reflect the comprehensive contribution of energy storage to the safety, reliability, and flexibility of the power grid. The evaluation results often underestimate the actual application value of energy storage, affecting the investment decisions of energy storage projects. Secondly, traditional evaluation methods mostly use static analysis methods, ignoring the dynamic characteristics of energy storage value changing over time and scenarios, and failing to fully consider the impact of factors such as grid load growth on the value of energy storage, making it difficult to accurately reflect the value differences and changing patterns of energy storage in different application scenarios.

[0012] Therefore, how to systematically characterize the dynamic evolution of energy storage value and economy, and evaluate the value of energy storage system under different grid load growth and grid operation conditions through scenario analysis. The application of energy storage on the grid side as a flexible regulation resource is an urgent problem to be solved. Summary of the invention

[0013] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a comprehensive evaluation method of energy storage value-economy based on system dynamics, which solves the problems in the above-mentioned background technology.

[0014] The object of the present invention is achieved by: a comprehensive evaluation method of energy storage value-economy based on system dynamics, which comprises:

[0015] Step 1: Determine the system boundaries and evaluation objectives;

[0016] Step 2: Establish an economic evaluation system for the life cycle of energy storage projects;

[0017] Step 3: Identify and evaluate the comprehensive alternative value of energy storage;

[0018] Step 4: Construct an energy storage value-economic evaluation model based on system dynamics theory;

[0019] Step 5: Based on the results of value assessment and economic assessment, conduct a comprehensive assessment to determine whether the criteria for various state variables exceed the threshold T; and give an evaluation conclusion through multi-variable comprehensive judgment.

[0020] By establishing a dynamic model that includes the energy storage value subsystem and the economic subsystem, a unified evaluation of the value and economy of the energy storage system throughout its life cycle is achieved. The system depicts the multi-dimensional value chain of energy storage and its dynamic evolution characteristics, accurately evaluates the technical and economic feasibility of energy storage replacing traditional power grids, and provides a quantitative basis for investment decisions and cost recovery mechanism design of energy storage projects. A comprehensive evaluation value chain and economic chain for energy storage are established. The energy storage value chain includes direct value (annualized grid investment replacement) + indirect value (spare capacity, power supply reliability, environmental benefits), and the economic chain includes costs (investment, operation and maintenance, decommissioning) and benefits (grid-connected power generation, valley filling and peak regulation, capacity leasing); the energy storage replacement value return coefficient is set as a comprehensive evaluation indicator for the value analysis of energy storage replacement grid construction.

[0021] 1. A comprehensive energy storage value-economic evaluation model was established to achieve a comprehensive evaluation of energy storage projects. For the first time, value evaluation and economic evaluation were unified under the system dynamics framework, overcoming the limitations of traditional methods of split evaluation and providing more comprehensive and accurate evaluation results.

[0022] Second, a dynamic evaluation mechanism has been established to reflect the characteristics of the value of the energy storage system changing over time, taking into account dynamic factors such as load growth and equipment aging. The evaluation results are more in line with the actual situation, improving the accuracy and reliability of decision support.

[0023] 3. Through the system dynamics model, various values ​​can be quantified to accurately evaluate the cost and benefits of the project throughout its life cycle. This reduces the risk of investment decisions. It also supports differentiated evaluation, which is suitable for different types of energy storage application scenarios. The evaluation parameters can be adjusted according to the specific situation, and the evaluation results are more targeted.

[0024] Furthermore, the system boundary is determined according to the type of energy storage application scenario; including: identifying energy storage projects, identifying whether the energy storage projects are of the type that delays the expansion and upgrading of transmission and distribution, solves seasonal load overload, or solves the overload of the substation and the absorption of new energy; collecting and setting basic parameters required for evaluation, including load demand characteristics, demand duration, frequency and cycle, energy storage system parameters, energy storage type, charging and discharging efficiency and system attenuation rate, as well as economic parameters, benchmark discount rate and operation and maintenance rate.

[0025] The economic evaluation system for the energy storage project life cycle is established as follows:

[0026] Carry out cost accounting, including initial investment cost, operation and maintenance cost, and decommissioning cost; then calculate various types of benefits, including grid-connected power generation benefits, valley-filling and peak-shaving benefits, and capacity leasing benefits;

[0027] The energy storage investment cost = energy storage capacity × energy storage unit investment,

[0028] Operating cost = energy storage construction investment × operating rate, and the income is calculated according to the corresponding calculation formula.

[0029] The identification and evaluation of the comprehensive replacement value of energy storage includes calculating the direct value and indirect value of the energy storage system respectively; the direct value is the annualized grid investment replacement value, and the calculation formula is:

[0030] Annualized grid investment replacement value = grid construction investment × (1-grid residual value rate) × grid discount rate × (1 + grid discount rate) ^ grid operation life / ((1 + grid discount rate) ^ (grid operation life - 1) + grid operation and maintenance fee);

[0031] Indirect value includes the value of reducing backup capacity, the value of improving power supply reliability and the value of environmental benefits, which are quantified using corresponding calculation formulas.

[0032] The energy storage value economic evaluation model based on system dynamics theory includes:

[0033] Carry out variable type classification, and divide the variables in the system into state variables, rate variables, auxiliary variables and constant parameters;

[0034] The state variables include energy storage replacement value return coefficient, energy storage investment NPV, load demand, energy storage value and grid construction investment;

[0035] The rate variables include annualized investment in alternative energy storage, total replacement value, cash inflows, and cash outflows;

[0036] The auxiliary variables include energy storage capacity, energy storage construction investment and charging price;

[0037] The constant parameters include power outage duration, energy storage unit investment and energy storage operation life.

[0038] Establish a causal relationship diagram between variables, construct the causal chain of the energy storage value subsystem and the economic subsystem respectively, and analyze the interaction between the two subsystems; construct the system's stock-flow model, establish the corresponding mathematical equations, set the initial values ​​of the variables and the simulation time step.

[0039] Calculate key evaluation indicators, including:

[0040] Energy storage replacement value return coefficient = total replacement value / annualized investment in alternative energy storage, and energy storage investment net present value NPV = cash inflow-cash outflow, discount rate, 0, 1;

[0041] Then a sensitivity analysis is performed to analyze the impact of the parameters of heavy load duration and load growth rate on the evaluation results.

[0042] The cost-economic model of the initial investment cost is,

[0043] I=(C p +C E )×E es

[0044] Among them, C p is the unit cost of non-battery equipment in the energy storage system, C E is the unit cost of the battery system, E es is the rated capacity of the battery system;

[0045] The annual operation and maintenance cost of the energy storage device is related to its operating conditions, including the staff wages, insurance, repair costs and other operating costs of the energy storage system. The annual growth rate of its operation and maintenance cost is 2%. Its operation and maintenance cost C is expressed as:

[0046] C=I×γ×[1+(n-1)×i2]

[0047] Among them, γ represents the operation and maintenance fee rate, i2 represents the annual growth rate of operation and maintenance costs, and n represents the number of years of operation;

[0048] The decommissioning cost is the difference between the disposal cost and the residual value.

[0049]

[0050] Where: C sv The decommissioning cost of the project; is the ratio coefficient of processing cost to system capacity; α is the residual value rate of fixed assets;

[0051] After completing the division of application scenarios, train the spatiotemporal correlation model for each application scenario.

[0052] The calculation method for delaying the investment in transmission and distribution facilities for the comprehensive replacement value identification and evaluation of energy storage is:

[0053] W1=λ d ×C d ×P max ×η

[0054] Where W1 represents the value of energy storage in delaying the investment in transmission and distribution equipment; d is the fixed asset depreciation rate of power distribution equipment; C d P is the unit capacity cost of power distribution equipment; max is the rated power of electrochemical energy storage, η is the charge and discharge efficiency of energy storage;

[0055] If the time value coefficient and different operating life cycles are taken into account, the replacement value can be converted into the annualized grid investment replacement value of energy storage.

[0056] W1′=AC d ×Pmax ×η

[0057] AC d =C d ×(1-λ)×ω+C d ×δ

[0058] Among them, AC d is the annual value of grid investment per unit power, is the sum of the annual value of grid investment over its entire life cycle and the annual operation and maintenance fee, and C d is the grid investment per unit power, λ is the residual value rate, δ is the operation and maintenance rate, and ω is the capital recovery coefficient.

[0059] The beneficial effects of the present invention are as follows: a comprehensive energy storage evaluation value chain and economic chain are established. The energy storage value chain includes direct value (annualized grid investment replacement) + indirect value (spare capacity, power supply reliability, environmental benefits), and the economic chain includes costs (investment, operation and maintenance, retirement) and benefits (grid-connected power generation, valley filling and peak regulation, capacity leasing); an energy storage replacement value return coefficient is set as a comprehensive evaluation indicator for the value analysis of energy storage replacement grid construction.

[0060] 1. A comprehensive energy storage value-economic evaluation model was established to achieve a comprehensive evaluation of energy storage projects. For the first time, value evaluation and economic evaluation were unified under the system dynamics framework, overcoming the limitations of traditional methods of split evaluation and providing more comprehensive and accurate evaluation results.

[0061] Second, a dynamic evaluation mechanism has been established to reflect the characteristics of the value of the energy storage system changing over time, taking into account dynamic factors such as load growth and equipment aging. The evaluation results are more in line with the actual situation, improving the accuracy and reliability of decision support.

[0062] 3. Through the system dynamics model, various values ​​can be quantified to accurately evaluate the cost and benefits of the project throughout its life cycle. This reduces the risk of investment decisions. It also supports differentiated evaluation, which is suitable for different types of energy storage application scenarios. The evaluation parameters can be adjusted according to the specific situation, and the evaluation results are more targeted. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a cause-effect relationship diagram of the energy storage value subsystem of the present invention;

[0064] Figure 2 is a cause-and-effect diagram of the energy storage economic subsystem of the present invention;

[0065] Figure 3 It is a technical solution diagram of the present invention. DETAILED DESCRIPTION

[0066] The present invention is further described in detail below in conjunction with the accompanying drawings. It should be pointed out that it is only for the purpose of more clearly describing and explaining the present invention.

[0067] like Figure 1-3 As shown, this embodiment discloses a comprehensive evaluation method of energy storage value-economy based on system dynamics, which includes:

[0068] Step 1: Determine the system boundary and evaluation objectives. Determine the system boundary based on the energy storage application scenario type.

[0069] Step 2: Establish an economic evaluation system for the entire life cycle of energy storage projects;

[0070] Step 3: Identification and evaluation of comprehensive alternative value of energy storage;

[0071] Step 4: Construct an energy storage value-economic evaluation model based on system dynamics theory;

[0072] Step 5: Based on the results of value assessment and economic assessment, conduct a comprehensive assessment to determine whether the criteria for various state variables exceed the threshold T; and give an evaluation conclusion through multi-variable comprehensive judgment.

[0073] The process of determining the system boundaries and evaluating the objectives in step 1 includes:

[0074] Step 1.1: First, identify whether the energy storage project is for delaying the expansion and upgrade of transmission and distribution capacity, solving seasonal load problems, or solving regional load problems and accommodating new energy.

[0075] Step 1.2: Collect and set the basic parameters required for the evaluation, including load demand characteristics (including demand duration, frequency and cycle), energy storage system parameters (including energy storage type, charging and discharging efficiency, system attenuation rate), and economic parameters (including benchmark discount rate, operation and maintenance fee rate, etc.).

[0076] In step 2, cost accounting is first performed, including initial investment cost, operation and maintenance cost, and decommissioning cost; then various benefits are calculated, including grid-connected power generation benefits, valley-filling and peak-shaving benefits, and capacity leasing benefits. Among them, energy storage investment cost = energy storage capacity × energy storage unit investment, operating cost = INITIAL (energy storage construction investment × operating rate), and various benefits are calculated according to the corresponding calculation formula.

[0077] In step 3, the direct value and indirect value of the energy storage system are calculated separately. The direct value is mainly the annualized grid investment replacement value, and the calculation formula is annualized grid investment replacement value = INITIAL (grid construction investment × (1-grid residual value rate) × grid discount rate × (1 + grid discount rate) ^ grid operation years / ((1 + grid discount rate) ^ grid operation years - 1) + grid operation and maintenance fees); the indirect value includes the value of reducing standby capacity, improving power supply reliability and environmental benefit value, which are quantified using the corresponding calculation formulas.

[0078] Constructing a value economics model based on system dynamics theory

[0079] Step 1.1: Classify the variables by type, and divide the key variables in the system into state variables (including energy storage replacement value return coefficient, energy storage investment NPV, load demand, energy storage value, grid construction investment), rate variables (including annualized investment in alternative energy storage, total replacement value, cash inflow, cash outflow, etc.), auxiliary variables (including energy storage capacity, energy storage construction investment, charging price, etc.) and constant parameters (including power outage duration, energy storage unit investment, energy storage operation life, etc.).

[0080] Step 1.2: Establish a causal relationship diagram between variables, construct the causal chain of the energy storage value subsystem and the economic subsystem respectively, and analyze the interaction between the two subsystems.

[0081] Step 1.3: Construct the stock-flow model of the system, establish the corresponding mathematical equations, set the initial values ​​of variables and the simulation time step.

[0082] In step 5, key evaluation indicators are calculated, including the energy storage replacement value return coefficient = total replacement value / annualized investment in alternative energy storage, and the energy storage investment net present value NPV = NPV((cash inflow-cash outflow), discount rate, 0, 1); then a sensitivity analysis is performed, focusing on the impact of key parameters such as heavy load duration and load growth rate on the evaluation results.

[0083] The method created by the present invention establishes a comprehensive evaluation value chain and economic chain for energy storage. The energy storage value chain includes direct value (annualized grid investment replacement) + indirect value (spare capacity, power supply reliability, and environmental benefits). The economic chain includes costs (investment, operation and maintenance, and retirement) and benefits (grid-connected power generation, valley filling and peak regulation, and capacity leasing). The energy storage replacement value return coefficient is set as a comprehensive evaluation indicator for the value analysis of energy storage replacement grid construction.

[0084] The specific process is as follows:

[0085] Step 1: Determine system boundaries and evaluation objectives.

[0086] Analyze the economic factors affecting energy storage grid connection, analyze the changes in operating costs and revenues of power grid companies, and determine the changes in relevant economic factors caused by energy storage and the corresponding changes.

[0087] This step first classifies and identifies energy storage application scenarios. For scenarios that delay the expansion and upgrade of transmission and distribution, the main judgment is made by analyzing whether the load of power grid equipment exceeds the rated capacity, whether there are land resource constraints, and whether the load growth shows obvious trend characteristics; for scenarios that solve seasonal overload, the main identification is made by analyzing whether the load shows obvious seasonal fluctuations, whether the overload has periodic characteristics, and whether the load rate fluctuates greatly; for scenarios that solve overload in substations and new energy consumption, it is necessary to determine whether the load rate of the substation transformer exceeds the design value.

[0088] After completing the scene identification, basic parameters are collected and set. Load demand characteristic parameters include demand duration (recording the duration of heavy load), demand frequency (statistical daily average number of heavy loads), demand cycle (determining the annual number of heavy load days) and load growth rate (analyzing historical data to determine the growth trend); energy storage system technical parameters include energy storage type selection, charge and discharge efficiency determination, system attenuation rate setting, cycle life determination and discharge depth setting; economic parameters include benchmark discount rate, operation and maintenance fee rate, equipment residual value rate and processing cost coefficient, etc.

[0089] Next, determine the evaluation boundaries, including time boundaries, space boundaries and evaluation dimensions. The time boundary needs to determine the evaluation period (usually the design life of the energy storage system), set the time step (determine the simulation accuracy based on the load characteristics) and clarify the construction period (including the construction and installation time of the energy storage system); the spatial boundary needs to determine the scope of influence (the scope of grid equipment and users involved), define the system boundary (clarify the scope of action of alternative solutions) and identify related systems (other systems that interact with the energy storage system); the evaluation dimensions include technical dimensions (system performance and reliability requirements), economic dimensions (investment benefits and cost recovery requirements) and environmental dimensions (environmental benefit evaluation scope).

[0090] Finally, the evaluation objectives are set, including technical objectives, economic objectives and environmental objectives. Technical objectives require determining the required energy storage capacity, setting performance index requirements and clarifying the operational reliability requirements; economic objectives require setting investment payback period requirements, determining minimum rate of return requirements and clarifying cost control objectives; environmental objectives include setting carbon emission reduction targets, determining environmental protection benefit requirements and clarifying social benefit expectations.

[0091] Through the above-mentioned systematic parameter collection, boundary determination and goal setting, the foundation can be laid for the subsequent system dynamics modeling and evaluation analysis, ensuring the reliability and practicality of the evaluation results. The accurate setting of parameters and boundary conditions has a key impact on the accuracy of the entire evaluation process and results.

[0092] Step 2: Establish an economic evaluation system for the entire life cycle of energy storage projects;

[0093] Energy storage economic evaluation includes two parts: cost model and benefit model. The cost of energy storage system mainly includes initial investment cost, operation and maintenance cost, and decommissioning cost.

[0094] (1) Cost-effectiveness model:

[0095] The investment cost mainly includes the cost of power conversion equipment (including AC side transformer and circuit breaker rectifier / inverter system) and energy storage system cost (mainly battery pack and battery pack management system). Its investment cost I can be expressed as:

[0096] I=(C p +C E )×E es

[0097] Among them, C p is the unit cost of non-battery equipment in the energy storage system, C E is the unit cost of the battery system, E es is the rated capacity of the battery system.

[0098] The annual operation and maintenance cost of the energy storage device is related to its operating conditions, including the staff salary, insurance, repair costs and other operating costs of the energy storage system. The annual growth rate of its operation and maintenance cost is 2%. Its operation and maintenance cost C can be expressed as:

[0099] C=I×γ×[1+(n-1)×i2]

[0100] Among them, γ represents the operation and maintenance fee rate, i2 represents the annual growth rate of operation and maintenance cost, and n represents the number of years of operation.

[0101] The decommissioning cost is the difference between the disposal cost and the residual value.

[0102]

[0103] Where: C sv The decommissioning cost of the project; is the ratio of processing cost to system capacity; α is the residual value rate of fixed assets.

[0104] After completing the division of application scenarios, train the spatiotemporal correlation model for each application scenario.

[0105] (2) Revenue economics model:

[0106] The energy storage revenue model mainly includes grid-connected power generation revenue, valley-filling and peak-shaving revenue, and capacity leasing revenue. el for:

[0107] R el =N c ×E es×DOD×(P pe -P dis / θ)

[0108] Where N c Indicates the annual charging and discharging times of the grid-side energy storage, E es is the rated capacity of the energy storage system, DOD is the depth of charge and discharge, P pe is the discharge price, P dis is the charging price, and θ is the charging and discharging efficiency.

[0109] The upper limit of the peak-shaving compensation price quotation is temporarily set at 0.3 yuan / kWh.

[0110] R 峰 =E s ×P s

[0111] Among them, P 峰 E is the peak load auxiliary compensation standard; s , P s The trading volume and trading electricity price for valley filling and peak load regulation services.

[0112] The annual income of grid-side energy storage participating in capacity leasing services is:

[0113] R r =P es ×P le

[0114] Where P es Indicates the energy storage rated power, P le Represents the annual rental price per unit capacity of energy storage.

[0115] Step 3: Identification and evaluation of comprehensive alternative value of energy storage;

[0116] Value identification and assessment are carried out from four main aspects: power grid companies, power generation companies, power users and the environment.

[0117] (1) Calculation method for delayed investment in transmission and distribution facilities

[0118] W1=λ d ×C d ×P max ×η

[0119] Where W1 represents the value of energy storage in delaying the investment in transmission and distribution equipment; d is the fixed asset depreciation rate of power distribution equipment; C d P is the unit capacity cost of power distribution equipment; max is the rated power of electrochemical energy storage, and η is the charge and discharge efficiency of energy storage.

[0120] If the time value coefficient and different operating life cycles are taken into account, the replacement value can be converted into the annualized grid investment replacement value of energy storage.

[0121] W1′=AC d ×P max ×η

[0122] AC d =C d ×(1-λ)×ω+C d ×δ

[0123] Among them, AC d is the annual value of grid investment per unit power, is the sum of the annual value of grid investment over its entire life cycle and the annual operation and maintenance fee, and C d is the grid investment per unit power, λ is the residual value rate, δ is the operation and maintenance rate, and ω is the capital recovery coefficient, which is related to the discount rate and the operating life.

[0124] (2) Calculation method of system reserve capacity on the power generation side

[0125] W2=λ f ×C f ×P max ×η

[0126] Where W2 represents the benefit of energy storage in reducing system backup capacity; f is the fixed asset depreciation rate of spare equipment; C f The unit capacity cost of the spare equipment.

[0127] (3) The benefits of improving power supply reliability are:

[0128] W3=c×V DL ×Q ESS ×η

[0129] Where W3 represents the benefit of energy storage in improving power supply reliability; c is the number of power outages for users; V DL The GDP value created per unit of electricity; Q ESS The amount of electricity provided to the energy storage power station.

[0130] (4) Calculation of environmental benefit improvement:

[0131] W4=V ei ×Q ESS

[0132] Where W4 represents the environmental benefits generated by energy storage; V is the reduced pollutant treatment cost of the i-th electrochemical energy storage.

[0133] Step 4: Construct an energy storage value-economic evaluation model based on system dynamics theory;

[0134] The model building process is as follows:

[0135] Step 1: Causal relationship diagram construction

[0136] (1) Energy storage value causal chain

[0137] The value of energy storage consists of direct value and indirect value; the direct value mainly comes from the annualized grid investment replacement value; the indirect value includes reducing backup capacity, improving reliability and environmental protection value.

[0138] (2) Energy storage economic causal chain

[0139] The economic feasibility is determined by costs and benefits; costs include construction investment, operation and maintenance costs, and decommissioning costs; benefits include grid-connected power generation, valley filling and peak load regulation, and capacity leasing income.

[0140] (3) Subsystem interactions;

[0141] Guided by the modeling objectives, the influencing factors of energy storage are divided into energy storage value subsystem and energy storage economic subsystem. At the same time, these two systems influence and restrict each other and work together on the comprehensive benefits of energy storage. Energy storage capacity affects value realization and economic level; load characteristics determine value creation and profit acquisition; and electricity price mechanism affects economic and value assessment.

[0142] See the attached diagram for the cause-effect relationship of the energy storage value subsystem Figure 1 , the cause-effect relationship diagram of energy storage economic subsystem is attached Figure 2 .

[0143] Step 2: Variable type classification

[0144] According to the above causal relationship, a stock-flow model is established. The state variables include: energy storage replacement value return coefficient, energy storage investment NPV, load demand, energy storage value, and grid construction investment; the rate variables include: annualized investment in alternative energy storage, total replacement value, cash inflow, cash outflow, direct value, indirect value, load increment, substation capacity investment, and line length investment; other variables are auxiliary variables and constants.

[0145] Step 3: System stock-flow model

[0146] The mathematical equations for system dynamics are established, mainly including:

[0147] (1) Basic equation

[0148] Energy storage value = indirect value + direct value

[0149] Energy storage capacity = load regulation requirements × energy storage configuration duration

[0150] Energy storage construction investment = energy storage capacity during the energy storage construction period × energy storage unit investment

[0151] Energy storage replacement value return coefficient = total replacement value / annualized investment in alternative energy storage

[0152] (2) Profit equation

[0153] Valley filling peak load regulation income = peak load regulation compensation unit price × annual peak load regulation times × energy storage capacity / 10

[0154] Peak-to-valley difference income = energy storage capacity × annual discharge times × charge-discharge depth × (charge-discharge efficiency × (discharge price - (charge price - 0.1969)) - (1-charge-discharge efficiency) × charge price) / 10

[0155] Rental income = energy storage capacity × rental unit price × rental rate / 10

[0156] (3) Value equation

[0157] Annualized grid investment replacement value = INITIAL (grid construction investment × (1-grid residual value rate) × grid discount rate × (1 + grid discount rate) ^ grid operation life / ((1 + grid discount rate) ^ grid operation life - 1) + grid operation and maintenance fee)

[0158] Reduced reserve capacity value = unit capacity price × alternative grid power × 0.05 × 5 / 60 × 24 / 10000

[0159] The value of improving power supply reliability = unit price of improved reliability × alternative grid power × power outage duration / 10.

[0160] Existing energy storage evaluation methods often separate the value assessment and economic evaluation of energy storage, lack a unified evaluation framework, resulting in one-sided evaluation results and difficulty in supporting decision-making. Traditional evaluation methods are difficult to accurately reflect the complex value chain and dynamic characteristics of energy storage systems in different application scenarios. This is because the sources of income of energy storage systems are diverse (such as delaying grid investment, improving power supply reliability, environmental benefits, etc.), and there is mutual influence between various types of income.

[0161] The invention achieves a unified evaluation of the value and economy of the energy storage system throughout its life cycle by establishing a dynamic model that includes an energy storage value subsystem and an economic subsystem. The system depicts the multi-dimensional value chain of energy storage and its dynamic evolution characteristics, accurately evaluates the technical and economic feasibility of energy storage replacing traditional power grids, and provides a quantitative basis for investment decisions and cost recovery mechanism design of energy storage projects.

[0162] Through the system dynamics model, various values ​​are quantified to accurately evaluate the costs and benefits of the project throughout its life cycle. Reduce the risk of investment decisions. It also supports differentiated evaluation, which is suitable for different types of energy storage application scenarios. The evaluation parameters can be adjusted according to the specific situation, and the evaluation results are more targeted. A dynamic evaluation mechanism has been established to reflect the characteristics of the value of the energy storage system changing over time, taking into account dynamic factors such as load growth and equipment aging. The evaluation results are more in line with the actual situation and improve the accuracy and reliability of decision support; a comprehensive evaluation model of energy storage value-economic efficiency has been established to achieve a comprehensive evaluation of energy storage projects. For the first time, value evaluation and economic efficiency evaluation are unified under the system dynamics framework, overcoming the limitations of traditional methods of split evaluation and providing more comprehensive and accurate evaluation results.

[0163] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A comprehensive evaluation method of energy storage value-economy based on system dynamics, characterized in that: include: Step 1: Determine the system boundaries and evaluation objectives; Step 2: Establish an economic evaluation system for the life cycle of energy storage projects; Step 3: Identify and evaluate the comprehensive alternative value of energy storage; Step 4: Construct an energy storage value-economic evaluation model based on system dynamics theory; Step 5: Based on the results of value assessment and economic assessment, conduct a comprehensive assessment to determine whether the criteria for various state variables exceed the threshold T; The evaluation conclusion is given through comprehensive judgment of multiple variables.

2. The method for comprehensive evaluation of energy storage value and economic efficiency based on system dynamics according to claim 1 is characterized in that: The system boundary is determined according to the type of energy storage application scenario; include: Identify energy storage projects, and identify whether the energy storage projects are of the type that delay the expansion and upgrade of transmission and distribution capacity, solve seasonal overload, or solve overload in the substation area and absorb new energy; Collect and set the basic parameters required for the evaluation, including load demand characteristics, demand duration, frequency and cycle, energy storage system parameters, energy storage type, charging and discharging efficiency and system attenuation rate, as well as economic parameters, benchmark discount rate and operation and maintenance rate.

3. The method for comprehensive evaluation of energy storage value and economic efficiency based on system dynamics according to claim 1 is characterized in that: The economic evaluation system for the life cycle of energy storage projects includes: Carry out cost accounting, including initial investment cost, operation and maintenance cost, and decommissioning cost; then calculate various types of benefits, including grid-connected power generation benefits, valley-filling and peak-shaving benefits, and capacity leasing benefits; Energy storage investment cost = energy storage capacity × energy storage unit investment, Operating cost = energy storage construction investment × operating rate, and the income is calculated according to the corresponding calculation formula.

4. The method for comprehensive evaluation of energy storage value and economic efficiency based on system dynamics according to claim 1 is characterized in that: The identification and evaluation of the comprehensive replacement value of energy storage includes calculating the direct value and indirect value of the energy storage system respectively; the direct value is the annualized grid investment replacement value, and the calculation formula is: Annualized grid investment replacement value = grid construction investment × (1-grid residual value rate) × grid discount rate × (1 + grid discount rate) ^ grid operation life / ((1 + grid discount rate) ^ (grid operation life - 1) + grid operation and maintenance fee); Indirect value includes the value of reducing reserve capacity, the value of improving power supply reliability and the value of environmental benefits, which are quantified using corresponding calculation formulas.

5. The method for comprehensive evaluation of energy storage value and economic efficiency based on system dynamics according to claim 1 is characterized in that: The energy storage value economic evaluation model based on system dynamics theory includes: Carry out variable type classification, and divide the variables in the system into state variables, rate variables, auxiliary variables and constant parameters; The state variables include energy storage replacement value return coefficient, energy storage investment NPV, load demand, energy storage value and grid construction investment; The rate variables include annualized investment in alternative energy storage, total replacement value, cash inflows, and cash outflows; The auxiliary variables include energy storage capacity, energy storage construction investment and charging price; The constant parameters include power outage duration, energy storage unit investment and energy storage operation life.

6. The method for comprehensive evaluation of energy storage value and economic efficiency based on system dynamics according to claim 5 is characterized by: Establish a causal relationship diagram between variables, construct the causal chain of the energy storage value subsystem and the economic subsystem respectively, and analyze the interaction between the two subsystems; construct the system's stock-flow model, establish the corresponding mathematical equations, set the initial values ​​of the variables and the simulation time step.

7. The method for comprehensive evaluation of energy storage value and economic efficiency based on system dynamics according to claim 1 is characterized in that: Calculate key evaluation indicators, including: Energy storage replacement value return coefficient = total replacement value / annualized investment in alternative energy storage, and energy storage investment net present value NPV = cash inflow-cash outflow, discount rate, 0, 1; Then a sensitivity analysis is performed to analyze the impact of the parameters of heavy load duration and load growth rate on the evaluation results.

8. The method for comprehensive evaluation of energy storage value and economic efficiency based on system dynamics according to claim 3 is characterized by: The cost-economic model of the initial investment cost is, I=(C p +C E )×E es Among them, C p is the unit cost of non-battery equipment in the energy storage system, C E is the unit cost of the battery system, E es is the rated capacity of the battery system; The annual operation and maintenance cost of the energy storage device is related to its operating conditions, including the staff wages, insurance, repair costs and other operating costs of the energy storage system. The annual growth rate of its operation and maintenance cost is 2%. Its operation and maintenance cost C is expressed as: C=I×γ×[1+(n-1)×i2] Among them, γ represents the operation and maintenance fee rate, i2 represents the annual growth rate of operation and maintenance costs, and n represents the number of years of operation; The decommissioning cost is the difference between the disposal cost and the residual value. Where: C sv The decommissioning cost of the project; is the ratio coefficient of processing cost to system capacity; α is the residual value rate of fixed assets; After completing the division of application scenarios, train the spatiotemporal correlation model for each application scenario.

9. The method for comprehensive evaluation of energy storage value and economic efficiency based on system dynamics according to claim 4 is characterized by: The calculation method for delaying the investment in transmission and distribution facilities for the comprehensive replacement value identification and evaluation of energy storage is: W1=λ d ×C d ×P max ×η Where W1 represents the value of energy storage in delaying the investment in transmission and distribution equipment; d is the fixed asset depreciation rate of power distribution equipment; C d P is the unit capacity cost of power distribution equipment; max is the rated power of electrochemical energy storage, η is the charge and discharge efficiency of energy storage; If the time value coefficient and different operating life cycles are taken into account, the replacement value can be converted into the annualized grid investment replacement value of energy storage. W1′=AC d ×P max ×η AC d =C d ×(1-λ)×ω+C d ×δ Among them, AC d is the annual value of grid investment per unit power, is the sum of the annual value of grid investment over its entire life cycle and the annual operation and maintenance fee, and C d is the grid investment per unit power, λ is the residual value rate, δ is the operation and maintenance rate, and ω is the capital recovery coefficient.

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