A comprehensive feasibility assessment method for a highway energy exchange and integration microgrid project

Abstract

The application discloses a comprehensive feasibility evaluation method for a highway energy exchange and fusion micro-grid project, and proposes an evaluation process based on technical feasibility and economic feasibility; in view of the horizontal extension characteristic of the highway energy exchange and fusion micro-grid, the maximum power transmission distance under the maximum voltage deviation limit of an inverter is calculated to evaluate the technical feasibility of the project construction; in consideration of the factors of the power generation efficiency attenuation of photovoltaic components, the power generation benefit, emission reduction benefit and life cycle cost of the distributed photovoltaic of the micro-grid are calculated to evaluate the economic feasibility of the project construction, so that the comprehensive and collaborative evaluation of the technical feasibility and economic feasibility of the highway energy exchange and fusion micro-grid project is realized.

Description

Technical Field

[0001] This invention relates to the field of transportation energy integration microgrid planning, and more particularly to the field of feasibility assessment of distributed photovoltaic microgrid projects centered on highway service areas. Background Technology

[0002] In existing technologies, the evaluation of microgrids involves calculating the economic, environmental, and other benefits that the microgrid will bring after its construction, given a certain installed power capacity, and then comparing these benefits with the total costs of the project to assess the profitability of the project and, consequently, the feasibility of its construction.

[0003] The difference between AC / energy converged microgrids based on highways and conventional microgrids lies in the fact that the exploitable area for distributed photovoltaic (PV) power generation along highway slopes has a lateral extension characteristic along the east-west direction. Therefore, excessively long extension distances of AC / energy converged microgrids will result in transmission distances at the system's ends being much greater than at the beginning, leading to increased AC side voltages on the terminal PV inverters and impacting their lifespan and operational safety. However, if the extension distance is too short, the PV power generation benefits after project construction will not be sufficient to offset the project's construction costs. How to comprehensively consider the technical and economic feasibility of the project is a key issue in this unique application scenario. Existing methods cannot yet provide a coordinated assessment of the technical and economic feasibility of AC / energy converged microgrids on highways. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention discloses a comprehensive feasibility assessment method for highway integrated energy and electricity microgrid projects. It proposes an assessment process based on technical and economic feasibility to evaluate the comprehensive feasibility of highway integrated energy and electricity microgrid projects; considering the lateral extension characteristics of highway microgrids, it proposes a technical feasibility assessment method; and considering the multiple benefits of photovoltaic power generation and the cost over the entire life cycle, it proposes an economic feasibility assessment method.

[0005] The aforementioned highway integrated energy microgrid project utilizes the exploitable area of ​​distributed photovoltaic power generation centered on the service area to provide power to the highway along the route, forming a highway integrated energy microgrid.

[0006] A comprehensive feasibility assessment method for highway energy-integrated microgrid projects includes the following steps:

[0007] Step (1): Calculate the relationship between the extension distance of the microgrid transmission line and the AC side voltage of the photovoltaic inverter, calculate the maximum extendable distance of photovoltaics along the highway, and evaluate the technical feasibility of the highway AC-energy integrated microgrid project.

[0008] Step (2): Considering the gradual decline in photovoltaic module power generation efficiency, calculate the annual power generation of photovoltaic modules in year t within the operating cycle of the highway energy-integrated microgrid project under the maximum extendable distance, and determine the power generation revenue and emission reduction benefits of the highway energy-integrated microgrid project throughout its entire life cycle under the maximum extendable distance.

[0009] Step (3): Calculate the life cycle cost of the highway energy-integrated microgrid project.

[0010] Step (4): Calculate the internal rate of return of the highway energy-integrated microgrid project and evaluate the economic feasibility of the highway energy-integrated microgrid project.

[0011] I. Step (1)

[0012] Step (1) requires calculating the maximum extendable distance, i.e., the transmission distance, under the AC side voltage limit of the inverter based on various parameters such as the photovoltaic power collection method, transmission cable selection, and photovoltaic inverter selection in the design scheme of the highway AC-energy integrated microgrid project, and then evaluating the technical feasibility of the highway AC-energy integrated microgrid project. Therefore, step (1) can be further divided into the following 3 sub-steps.

[0013] Step 1: Calculate the AC side voltage U of the photovoltaic inverter after grid connection. PV With the rated voltage U of the microgrid in the service area n Voltage relationship between them:

[0014]

[0015] In the formula, P and Q represent the active power and reactive power transmitted by the photovoltaic grid-connected inverter, respectively, and R... L X L These are the resistance and reactance of the photovoltaic power generation transmission line, respectively.

[0016] Since the resistance of transmission lines in a low-voltage power grid is much greater than their reactance, the voltage relationship on photovoltaic transmission lines in a combined energy and power microgrid project can be approximated by the following formula:

[0017]

[0018] In the formula, L inV denoted as , where is the distance between the photovoltaic grid-connected inverter and the service area, and r is the resistance value per unit length of the transmission line.

[0019] Step 2: Calculate the maximum extendable distance, i.e., the transmission distance L, under the maximum voltage deviation limit of the inverter. max

[0020] A rise in AC side voltage of a photovoltaic inverter can negatively impact the lifespan of various power electronic components in the inverter equipment and the safe and stable operation of the microgrid. Therefore, it is necessary to consider the constraints... Calculate the maximum transmission distance under the maximum voltage deviation limit of the inverter. L max :

[0021]

[0022] In the formula, P is the maximum voltage deviation limit for the inverter. max This represents the maximum power output of the photovoltaic module.

[0023] Step 3: Assess the technical feasibility of the highway energy-integrated microgrid project.

[0024] Determine whether the design scheme of the highway energy-integrated microgrid project meets the maximum transmission distance constraint, i.e. whether it is technically feasible. If it is technically feasible, continue to execute steps (2)-(4) to evaluate the economic feasibility of the project. If it is technically infeasible, the design scheme of the energy-integrated microgrid extension range, transmission cable selection, photovoltaic inverter selection, etc. need to be adjusted, and step (1) should be executed again to evaluate the technical feasibility of the project.

[0025] II. Step (2)

[0026] Step (2) can be divided into 3 sub-steps.

[0027] Step 1: Calculate the annual power generation E of the photovoltaic modules in year t of the highway energy-integrated microgrid project within its operating cycle at the maximum extendable distance. PV，t

[0028] Based on the photovoltaic (PV) installed capacity in the design scheme of a highway integrated energy and electricity microgrid project, and considering the annual degradation of PV module power generation efficiency, calculate the annual power generation of the PV modules in year t of the project's operating cycle under the maximum extendable distance. E PV，t :

[0029] E PV,t =P n LT0(1-η PV ) t (Formula 4)

[0030] In the formula, P n Let L be the photovoltaic installed capacity per unit distance along the highway, T0 be the annual utilization hours of photovoltaic power generation in the area, and η be the installed capacity per unit distance along the highway. PV This is the degradation factor of the power generation capacity of photovoltaic modules.

[0031] Step 2: Calculate the power generation revenue of the highway integrated electric microgrid project in year t within its operating cycle at the maximum extendable distance. And the net present value of the project's power generation benefits over its entire life cycle at the maximum extendable distance.

[0032] The power generation revenue of the highway energy integration project includes the savings in electricity purchase costs when the photovoltaic power generation is self-consumed after the project's construction, and the revenue from selling surplus electricity to the grid. The savings in electricity purchase costs when the photovoltaic power generation is self-consumed can be represented by the difference between the microgrid load and the actual purchased electricity. The surplus photovoltaic power sold to the grid is the difference between the annual photovoltaic power generation and the savings in electricity purchase costs when the photovoltaic power generation is self-consumed. Therefore, the power generation revenue in year t of the project's operating cycle under the maximum extendable distance is... And the net present value of the project's power generation revenue over its entire life cycle at the maximum extendable distance. The following formula can be used to calculate:

[0033]

[0034]

[0035] In the formula, ρ b ρ s These are the electricity purchase price and grid connection price for the integrated electric and electric power grids along highways, respectively. L,t E b,t These represent the load electricity consumption and purchased electricity of the highway energy-integrated microgrid in year t, respectively, where T is the project's total life cycle and η is the discount rate.

[0036] Step 3: Calculate the emission reduction benefits of the highway energy-integrated microgrid project in year t of its operating cycle at the maximum extendable distance. Net present value of emission reduction benefits over the entire life cycle of the project at the maximum extendable distance.

[0037] The emission reduction benefits of a highway integrated photovoltaic (PV) microgrid project refer to the economic benefits resulting from the reduction of pollutant and carbon dioxide emissions due to the decrease in fossil fuel power generation after the project's construction. The emission reduction benefits of a highway integrated PV microgrid project in year t of its operating cycle at the maximum extendable distance are also described. and the net present value of emission reduction benefits over the entire life cycle at the maximum extendable distance. The following formula can be used to calculate:

[0038]

[0039]

[0040] In the formula, α i β represents the environmental value of the i-th emission substance. iIt is the emission difference coefficient between photovoltaic power generation and coal-fired power generation for the i-th emission substance per unit of power generation.

[0041] III. Step (3)

[0042] Step (3) calculates the total life-cycle cost of the highway energy-integrated microgrid project during the investment and construction phase, operation and maintenance phase, and decommissioning phase, which can be divided into three sub-steps.

[0043] Step 1: Calculate the investment and construction costs C of the highway energy-integrated microgrid project. con

[0044] Calculate the investment and construction costs of a highway integrated energy and electricity microgrid project, including the cost of photovoltaic modules (C). sol Cost of stent C str Inverter cost C inV Cost of transmission cable C cab and installation cost C set The project investment and construction phase costs are shown in the following formula:

[0045] C con =C sol +C str +C inv +C cab +C set (Formula 9)

[0046] The various costs associated with the investment and construction phase of the project can be approximated as linear and proportional to the power generation scale. Therefore, the investment and construction costs of the highway energy-integrated microgrid project can be simplified as follows:

[0047] C con =K con P n L (Formula 10)

[0048] In the formula, K con This is a constant representing the ratio of cost to photovoltaic installed capacity.

[0049] Step 2: Calculate the net present value of the entire life cycle of the operation and maintenance costs of the highway energy-integrated microgrid project.

[0050] Calculate the operation and maintenance costs of a highway integrated energy and energy microgrid project. Including maintenance costs in year t Loan interest costs

[0051]

[0052]

[0053]

[0054]

[0055] In the formula, μ is the proportion of annual maintenance cost to construction cost, ω is the loan ratio, and λ is the annual loan interest rate. M represents the net present value of the operation and maintenance phase costs over the entire life cycle, and M is the loan term.

[0056] Step 3: Calculate the net present value of the decommissioning cost of the highway integrated energy and communication microgrid project over its entire life cycle.

[0057] Calculate the decommissioning cost C of a highway integrated energy and power microgrid project. sc This refers to the difference between the cost of disposing of abandoned equipment and the residual value of the equipment.

[0058] C sc =α sc P n LR(Formula 15)

[0059]

[0060] In the formula, α sc R is the cost factor for disposing of waste photovoltaic modules and related equipment per unit capacity, where R is the residual value of the project equipment. It is the net present value of the total life-cycle cost of scrapping.

[0061] IV. Step (4)

[0062] Step (4) involves calculating the internal rate of return of the highway energy-integrated microgrid project and assessing its economic feasibility, provided that the maximum extendable distance calculated in step (1) is met. This step can be divided into two sub-steps.

[0063] Step 1: Calculate the internal rate of return of the highway hybrid microgrid.

[0064] The internal rate of return (IRR) of a highway energy-integrated microgrid project refers to the discount rate at which the cumulative net present value (NPV) is zero during the calculation period. It represents the discount rate at which the project neither makes a profit nor incurs a loss throughout its entire life cycle.

[0065] The internal rate of return (IRR) of a highway-connected energy-integrated microgrid project can be calculated by solving the following formula:

[0066]

[0067] Linear interpolation can be used for calculation, assuming the discount rate is η. a At that time, the project's net present value is N. a Assume the discount rate is η bAt that time, the project's net present value is N. b The internal rate of return (IRR) of the highway energy-integrated microgrid project is:

[0068]

[0069] The calculation of the internal rate of return (IRR) of the highway energy-integrated microgrid project requires the net present value of the life-cycle power generation revenue obtained in step (2). and net present value of emission reduction benefits throughout the entire life cycle And the investment and construction cost C of the highway energy-integrated microgrid calculated in step (3). con The net present value of the project's operation and maintenance phase costs over its entire life cycle. Net present value of project scrapping costs over its entire life cycle

[0070] Step 2: Assess the economic feasibility of highway energy-integrated microgrid projects.

[0071] If the internal rate of return is greater than the benchmark rate of return under the condition of satisfying the technical feasibility of step (1), then the highway energy-integrated microgrid project is economically feasible; if the internal rate of return is less than the benchmark rate of return or does not satisfy the technical feasibility of step (1), then the highway energy-integrated microgrid project is not economically feasible.

[0072] This invention proposes an assessment process based on technical and economic feasibility to evaluate the comprehensive feasibility of highway integrated energy and electricity microgrid projects. Considering the lateral extension characteristics of highway integrated energy and electricity microgrids, the maximum transmission distance is calculated under the maximum voltage deviation limit of the inverter to assess the technical feasibility of the project. Taking into account the degradation of photovoltaic module power generation efficiency, the power generation benefits, emission reduction benefits, and life-cycle costs of distributed photovoltaic power in the microgrid are calculated to assess the economic feasibility of the project. This achieves a comprehensive and coordinated assessment of the technical and economic feasibility of highway integrated energy and electricity microgrid projects. Attached Figure Description

[0073] Figure 1 Flowchart of a comprehensive feasibility assessment method for a highway energy-integrated microgrid project Detailed Implementation

[0074] Example:

[0075] The comprehensive feasibility assessment method for highway integrated energy microgrid projects was used to conduct a comprehensive assessment of the technical and economic feasibility of a highway integrated energy microgrid project.

[0076] Step (1): Calculate the maximum extendable distance of the highway energy-integrated microgrid project and assess its technical feasibility.

[0077] Taking the distributed photovoltaic construction scheme on the highway slope of a certain energy-integrated microgrid project as an example, the service area grid-side voltage U n =0.38kV, the inverter's rated output voltage is 0.4kV, and the maximum voltage deviation at the inverter's grid connection point is 7% of the rated value, therefore The maximum power output P of a single photovoltaic inverter connected to a photovoltaic power generation unit max =28kW, the resistivity of the transmission cable r =0.42Ω / km, the installed length along the highway service area is 1.5km on one side, and the total installed length of photovoltaic power on both sides is L =3km.

[0078] ①The maximum extendable distance, i.e. the transmission distance, can be calculated according to formula (3) in step (1) of the invention.

[0079]

[0080] ② Based on step 3 of step (1) in the invention description, determine that L < 2L max Therefore, the design scheme meets the technical feasibility requirements. Continue with steps (2)-(4) to evaluate the economic feasibility of the highway energy-integrated microgrid project.

[0081] Step (2): Considering the gradual decline in photovoltaic module power generation efficiency, calculate the annual power generation of photovoltaic modules in year t within the operating cycle of the highway energy-integrated microgrid project under the maximum extendable distance, and determine the power generation revenue and emission reduction benefits of the highway energy-integrated microgrid project throughout its entire life cycle under the maximum extendable distance.

[0082] The photovoltaic installed capacity per unit distance under the project plan, P n =800kW / km, the annual utilization hours of photovoltaic power generation in this area T0 = 1220h, and the photovoltaic module power generation capacity attenuation factor η PV =0.006, annual load electricity consumption E L,t =348,000 kWh, discount rate η = 8%, project life cycle T = 20 years, electricity purchase price is 0.8 yuan / kWh, and grid connection price is 0.39 yuan / kWh.

[0083] ①Calculate the annual power generation E of the photovoltaic modules in year t of the highway energy-integrated microgrid project under the maximum extendable distance during the operation cycle of the project, based on step (2) of the invention content. PV,t The annual electricity purchase volume was calculated, and the results are shown in the table below:

[0084]

[0085] ②Calculate the net present value of power generation benefits over the entire life cycle of the highway AC-energy integrated microgrid project at the maximum extendable distance, according to step 2 in step (2) of the invention content.

[0086] According to formula (4) in step (1), formula (5) and formula (6) in step (2) of the invention.

[0087] E PV,t =P n LT0(1-η PV ) t

[0088]

[0089]

[0090] The net present value of power generation benefits over the entire life cycle of the highway integrated energy microgrid project was calculated at the maximum extendable distance. Ten thousand yuan.

[0091] ③ Calculate the net present value of emission reduction benefits over the entire life cycle of the highway energy-integrated microgrid project at the maximum extendable distance, based on step 3 of step (2) in the invention content.

[0092] The emission factors for carbon dioxide and pollutants are shown in the table below:

[0093]

[0094] According to formulas (7) and (8) in step (2) of the invention description.

[0095]

[0096]

[0097] The net present value of emission reduction benefits over the entire life cycle of the highway energy-integrated microgrid project was calculated at the maximum extendable distance. Ten thousand yuan.

[0098] Step (3): Calculate the life cycle cost of the highway energy-integrated microgrid project.

[0099] The ratio constant K of the energy integration project characterization cost to photovoltaic installed capacity con =3240 yuan / kW, maintenance cost percentage μ = 1%, loan ratio ω = 70%, annual loan interest rate λ = 4.9%, equipment residual value R = 10%*C con Loan term M = 15 years, waste component disposal cost coefficient α sc =600 yuan / kW.

[0100] ①Calculate the investment and construction cost C of the highway energy-integrated microgrid project according to step 1 of step (3) in the invention content. con .

[0101] According to formula (10) in step (3) of the invention content.

[0102] C con =K con P n L

[0103] The project investment and construction phase cost C was calculated. con =K con P n L = 7.776 million yuan.

[0104] ②Calculate the net present value of the entire life cycle cost of the operation and maintenance phase of the highway energy-integrated microgrid project according to step 2 of step (3) in the invention content.

[0105] According to formulas (11)-(14) in step (3) of the invention content.

[0106]

[0107]

[0108]

[0109]

[0110] Calculate the net present value of the project's operation and maintenance phase costs over its entire life cycle. Ten thousand yuan.

[0111] ③ Calculate the net present value of the entire life cycle of the decommissioning cost of the highway energy-integrated microgrid project according to step 3 in step (3) of the invention content.

[0112] According to formulas (15)-(16) in step (3) of the invention content.

[0113] C sc =α sc P n LR

[0114]

[0115] Calculate the project's scrap cost over its entire life cycle net present value. Ten thousand yuan

[0116] Step (4): Calculate the internal rate of return of the highway energy-integrated microgrid project and evaluate the economic feasibility of the highway energy-integrated microgrid project.

[0117] ① Calculate the internal rate of return of the highway energy-integrated microgrid project according to step (4) of the invention.

[0118] According to the above calculations in the embodiment, the discount rate η can be obtained. a When the net present value (NPV) is 8%, the project's N is... a = 4,491,700 yuan, when the discount rate η a When the net present value (NPV) is 16%, the NPV can be obtained based on the above parameters and calculation process. b =-324,900 yuan.

[0119] According to formula (18) in step (4) of the invention content.

[0120]

[0121] The calculated internal rate of return (IRR) for the project is 15.4%.

[0122] ② According to step 2 in step (4) of the invention, the internal rate of return (IRR) of the project is determined to be 15.4%, which is higher than the benchmark rate of return of 8%, and the project meets the economic feasibility.

[0123] By using steps (1) to (4) of the comprehensive feasibility assessment method for highway energy-integrated microgrid projects, the technical and economic feasibility of the project is assessed, and the results show that the highway energy-integrated microgrid project meets the comprehensive feasibility requirements for investment and construction.

Claims

1. A comprehensive feasibility assessment method for highway energy-integrated microgrid projects, characterized in that, The method includes the following steps: Step (1): Assess the technical feasibility of the highway AC-powered microgrid project, specifically including: calculating the AC side voltage of the photovoltaic inverter after grid connection. With the rated voltage of the microgrid in the service area Voltage relationship between them: In the formula, , These represent the active power and reactive power transmitted by the photovoltaic grid-connected inverter, respectively. , These are the resistance and reactance of the photovoltaic power generation transmission line, respectively. The voltage relationship can be approximated using the following formula: In the formula, The distance between the photovoltaic grid-connected inverter and the service area. The resistance value per unit length of the transmission line; According to the constraints Calculate the maximum transmission distance under the maximum voltage deviation limit of the inverter. : In the formula, This is the maximum voltage deviation limit for the inverter. This represents the maximum power output of the photovoltaic module. Determine whether the design scheme of the highway energy-integrated microgrid project meets the maximum transmission distance constraint. If it does, the technology is feasible, and continue to execute steps (2)-(4); if it does not meet the constraint, the design scheme needs to be adjusted and step (1) needs to be executed again. Step (2): Determine the net present value of power generation revenue and the net present value of emission reduction benefits of the highway energy-integrated microgrid project throughout its entire life cycle, specifically including: Calculate the project's operating cycle within the maximum extendable distance. Annual power generation of photovoltaic modules : In the formula, This refers to the photovoltaic installed capacity per unit distance along the highway. The length of photovoltaic installations along the highway. This refers to the annual utilization hours of photovoltaic power generation. This is the degradation factor of the power generation capacity of photovoltaic modules. For the year of operation; Calculate the project number Annual electricity revenue and net present value of power generation revenue over the entire life cycle : In the formula, These refer to the electricity purchase price and the grid connection price for the integrated electric power grid on highways. The first Annual load electricity consumption and purchased electricity For the entire project lifecycle, The discount rate; Calculate the project number Annual emission reduction benefits and net present value of emission reduction benefits throughout the entire life cycle : In the formula, For the first The environmental value of these emissions The first division of photovoltaic power generation and coal-fired power generation per unit of power generation Emission differential coefficient for various emission substances; Step (3): Calculate the net present value of the total life-cycle cost of the highway energy-integrated microgrid project, specifically including: Calculate the cost of the investment and construction phase : Or simplified to: In the formula, , , , , These are the costs of photovoltaic modules, mounting systems, inverters, transmission cables, and installation. This serves as a constant representing the ratio of cost to photovoltaic installed capacity. Calculate the net present value of the entire life cycle of operation and maintenance costs. : In the formula, For the first Annual operating and maintenance costs For the first Annual maintenance costs For the first Annual loan interest cost The percentage of annual maintenance costs to construction costs. For loan ratio, The annual interest rate for the loan. The loan term; Calculate the net present value of the entire life cycle for the cost of scrapping. : In the formula, The cost factor for handling waste photovoltaic modules and related equipment per unit capacity. The residual value of the project's equipment; Step (4): Under the technical feasibility condition of meeting the maximum extendable distance calculated in Step (1), evaluate the economic feasibility of the highway energy-integrated microgrid project, specifically including: Calculate the internal rate of return That is, to find the discount rate that makes the following equation true: The calculation is performed using linear interpolation, and the formula is as follows: In the formula, Let the two discount rates be assumed. This represents the project's net present value at the corresponding discount rate. If the internal rate of return is greater than the benchmark rate of return, then it is economically feasible; otherwise, it is not.

2. The method according to claim 1, characterized in that, Step (1) includes: determining the length of photovoltaic installations along the highway in the design scheme. Is it less than .

3. The method according to claim 1, characterized in that, The power generation revenue mentioned in step (2) This includes the savings in electricity purchase costs when photovoltaic power generation is used for self-consumption and the revenue from selling surplus electricity to the grid.

4. The method according to claim 1, characterized in that, The cost items in the investment and construction phase cost described in step (3) , , , , All are directly proportional to the scale of power generation.

5. The method according to claim 1, characterized in that, The internal rate of return mentioned in step (4) It is the discount rate that makes the cumulative net present value of a project zero over its entire life cycle.

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