Power distribution network transformer carbon footprint analysis method based on life cycle evaluation

Abstract

The invention discloses a power distribution network transformer carbon footprint analysis method based on life cycle evaluation, which is based on a life cycle evaluation method, takes a transformer with the capacity of 200kVA as an example, calculates the carbon emission and the total energy demand of the whole life cycle, and further analyzes the carbon emission in each stage. Research finds that the carbon emission with the highest proportion is the operation stage and accounts for 99.03% of the whole life cycle, the waste recovery stage effectively reduces the influence of the carbon emission on the environment, the technology in the production and manufacturing process is improved, more energy-saving and efficient devices are adopted, and the carbon emission can be effectively reduced. Sensitivity analysis shows that the silicon steel sheets have obvious influence on carbon emission in the life cycle of the power distribution network transformer, and the higher the silicon steel sheets are, the lower the carbon emission is.

Description

Technical Field

[0001] The present invention relates to the field of carbon footprint analysis of distribution network transformers, and in particular to a carbon footprint analysis method of distribution network transformers based on life cycle assessment. Background Art

[0002] Distribution network transformers are key equipment for power transmission and distribution, and are also the main equipment for delivering electricity to thousands of households. However, studies have shown that 60% of the energy loss in the distribution network comes from distribution network transformers. Therefore, exploring the carbon footprint of each component of the distribution network transformer is of great significance for low-carbon emission reduction.

[0003] The current product low-carbon evaluation standards include seven categories of products, mainly concentrated in the fields of construction, mining and railways. These seven fields have professional and complete evaluation standards and rich evaluation index system research, but do not involve the carbon footprint analysis and low-carbon evaluation standards of distribution network transformers. At present, the low-carbon research on power transformers is mainly focused on large transformers, and there is little low-carbon research on distribution network transformers. The random forest and support vector machine algorithms are used to carry out the research and analysis of the whole life cycle of power transformers, and the main factors affecting carbon emissions are determined. The low-carbon optimization and carbon footprint analysis of power transformers are carried out based on digital twin technology. The carbon emissions of each component of the transformer are analyzed during the production process based on the whole life cycle, the key components of carbon emissions are determined, and a standard report on carbon footprint accounting is formed. Efficiency improvement technologies such as reactive power compensation, load balancing, and harmonic filtering are used to reduce the energy loss of distribution transformers, thereby reducing carbon dioxide emissions and economic costs in transformer operation.

[0004] Carbon footprint is a measure of the amount of greenhouse gases produced by a product in a specific period of time and the degree of impact on the environment. Its calculation covers the emission process of the product throughout its life cycle from production to waste recycling and disposal. Cumulative Energy Demand is an indicator that characterizes the energy consumption of the system, which refers to the sum of the total energy consumption over the entire life cycle of the product. As one of the core electrical equipment, distribution network transformers play an important role in ensuring the normal power supply of electrical equipment and ensuring the safety and reliability of the power system. The procurement volume has remained high for many years, and it is representative and exemplary for carrying out carbon footprint and low-carbon evaluation work. Combined with the internal structure of distribution network transformers and carbon emission activities in all links of the entire life cycle, based on the international mainstream carbon footprint accounting standards and advanced experience in low-carbon product evaluation, this paper explores the accurate carbon footprint accounting method and low-carbon evaluation system of distribution network transformers. Based on this, the present invention uses the Life Cycle Assessment (LCA) method to analyze the carbon emission characteristics of distribution network transformers in various links such as production and manufacturing, logistics and transportation, construction and installation, operation and maintenance, and decommissioning and recycling, in order to more accurately identify the impact of distribution network transformers at different life stages on the environment, and provide decision-making support for the design and development of distribution network transformers in my country.

[0005] Distribution Network Transformer Model

[0006] As a key power equipment connecting users, distribution network transformers are widely used in rural areas and cities, and play a vital role in the development of county economy. This paper selects the commonly used three-phase oil-immersed transformer as the research object. The transformer is mainly composed of a shell, an iron core, a winding, an oil tank, and high and low voltage bushings. The transformer model is as follows Figure 1 shown.

[0007] Basic parameters of distribution network transformers

[0008] The research object of this invention is the three-phase oil-immersed transformer of the distribution network. Its main materials and related parameters are given in Table 1. The core components of the transformer are mainly the iron core and winding. Clarifying the composition and source of the materials of the distribution network transformer is conducive to analyzing the carbon emission sources and carbon verification of each component.

[0009] Table 1 Basic parameters of transformer

[0010]

[0011] At present, the evaluation methods of low-carbon products are mainly concentrated on seven categories of products, such as silicate cement, flat glass, aluminum alloy building profiles, and small and medium-sized three-phase asynchronous motors. There is a lack of corresponding carbon evaluation methods for distribution network transformers. In * month of 20**, Wang Yanpeng et al.: Carbon footprint analysis of distribution network transformers based on life cycle assessment 4 systems, especially the research on carbon emissions of the whole process of distribution network transformers is even rarer. Bi Zijian et al. analyzed the carbon footprint composition of 10kV oil-immersed and dry-type transformers and the changes in carbon emissions of each part production process at different capacities, and clarified the key units of carbon emission reduction based on this. This study mainly focuses on the carbon emissions of various parts of the distribution network, and does not include the recycling stage that has developed rapidly in recent years. The product carbon footprint and total energy demand can effectively analyze the carbon emissions and energy consumption of distribution network transformers throughout their life cycle. This invention takes 200kVA oil-immersed transformers as the research object, uses Simapro software, and uses the LCA-RCEES database to calculate and analyze the carbon footprint and total energy demand of distribution network transformers using the life cycle assessment method. Summary of the invention

[0012] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a carbon footprint analysis method for distribution network transformers based on life cycle assessment.

[0013] To achieve the above object, the technical solution of the present invention is:

[0014] The carbon footprint analysis method of distribution network transformer based on life cycle assessment consists of the following steps:

[0015] Step 1: Determine the carbon footprint system boundary

[0016] Establish the accounting boundary of distribution network transformers. The whole life cycle of distribution network transformers includes the raw material acquisition stage, production and assembly stage, transportation stage, construction and installation stage, operation and use stage, and recycling and disposal stage. According to the whole life cycle method, the accounting boundary is determined from "cradle to grave";

[0017] Step 2: Determine the life cycle inventory data of distribution network transformers at different stages

[0018] This method is applicable to the calculation of carbon emissions from distribution network transformers of various models and capacities, but the type and content of raw materials need to be provided in the calculation.

[0019] Production stage

[0020] The production stage of distribution network transformers mainly involves the consumption of materials and energy, which will generate a large amount of carbon emissions. The carbon emissions in the production and manufacturing stage of distribution network transformers mainly include carbon emissions from raw material acquisition, production and assembly, including carbon emissions in the production and assembly process of steel plates, copper wires, silicon steel sheets, transformer oil, etc. The data of other components are difficult to obtain. Therefore, only the carbon emissions of the above components are considered in the production stage. The carbon emission calculation formula for the production stage of distribution network transformers is as follows:

[0021]

[0022] Where CF production is the carbon emission during the production of distribution network transformers, CF production·n They represent the carbon emissions of steel plates, copper wires, silicon steel sheets and transformer oil respectively. The carbon emission coefficients in the production and assembly stage are shown in Table 2:

[0023] Table 2 Carbon emission coefficients in the production and assembly stage

[0024]

[0025] Transportation Stage

[0026] The transportation method of raw materials, components and complete equipment of distribution network transformers is mostly road transportation. Road transportation produces 0.23kg of carbon dioxide per ton / kilometer and requires a total energy of 2.66MJ. The present invention estimates the transportation distance based on relevant research and reference. The comprehensive transportation distance of its materials is about 900km. The carbon emission calculation formula in the transportation stage is as follows:

[0027] CF transport =∑M×D i ×Ene per ×0.372 (2)

[0028] Where CF transport is the carbon emission in the transportation stage; M is the weight of the distribution network transformer; Di is the transportation distance; Ene per is the unit energy consumption of the transportation mode; 0.372 represents the carbon emission coefficient of gasoline and diesel. The carbon emission coefficient in the transportation stage is shown in Table 3:

[0029] Table 3 Carbon emission coefficients in the transportation stage

[0030]

[0031] Operational stage

[0032] According to the technical specification for the solidification of standardized materials for distribution networks issued by the State Grid Corporation of China headquarters, the life of distribution network transformers should be no less than 40 years. In the present invention, the service life is calculated as 40 years, and the annual operating time is generally 8760 hours. In the process of calculating carbon emissions, the power loss of the transformer is a key factor. Based on this, the calculation formula for the power loss of the transformer is given:

[0033]

[0034] In the formula, △A is the power loss, △P c is the transformer short-circuit loss, S is the transformer through capacity, S c is the rated capacity of the transformer, τ is the loss hours, △P0 is the no-load loss of the transformer, and T is the annual operating time of the transformer.

[0035] The operation phase of the distribution network transformer is the main phase of carbon emissions in the entire life cycle, accounting for more than 90%, which is much larger than the operation and maintenance of the equipment and the replacement of parts. Therefore, the carbon emissions in the transformer operation phase are processed as follows: the distribution network transformer has a service life of 40 years, and the annual operation time is 8760h. The power loss of the transformer is calculated to be 208720kWh. The carbon emission calculation formula for the operation phase of the distribution network transformer is as follows:

[0036] CF run =△A×Ene electricity (4)

[0037] Where CF run Ene is the carbon emission in the operation phase; electricity is the carbon emission coefficient of electricity. The carbon emission coefficients in the operation stage are shown in Table 4.

[0038] Table 4 Carbon emission coefficients during operation

[0039]

[0040] Waste recycling stage

[0041] At present, the recycling of transformers in my country's distribution network is mainly carried out through the unified auction of the State Grid and small batch processing by user enterprises.

[0042] The recycling and disassembly level is relatively extensive and cannot reach the level of green

[0043] Low carbon, low carbon and environmentally friendly level.

[0044] Referring to the recycling of distribution network transformers at home and abroad, the process adopts the green disassembly and recycling method, and the process is as follows:

[0045] ①: State Grid Corporation of China recycles retired transformers.

[0046] ②: Rely on recycling manufacturers to carry out green dismantling of transformers and extract transformer oil, silicon steel sheets, copper, aluminum and other metal materials.

[0047] ③: The extracted metal materials are processed by metal smelting enterprises.

[0048] ④: The metal materials extracted by metal smelting enterprises are reused by transformer manufacturers. At the same time, the disassembled transformer oil is also reused by transformer manufacturers.

[0049] ⑤: Transformer manufacturers use recycled materials to produce new transformers.

[0050] The structure of distribution network transformers is basically the same, and the recycled materials are also the same, mainly including silicon steel sheets, copper, aluminum and insulating oil, and the remaining materials are disposed of as municipal solid waste landfill. The carbon emission calculation formula for the waste recycling stage of distribution network transformers is as follows:

[0051] CF recycling =∑M×Ene m·per ×Ene n·energy (5)

[0052] Where, CF transport is the carbon emission in the transportation stage; M is the weight of the distribution network transformer; Ene m·per Ene is the unit energy consumption of waste treatment; n·energy is the carbon emission coefficient of waste treatment. The carbon emission coefficient in the waste recycling stage is shown in Table 5:

[0053] Table 5 Carbon emission coefficients in the waste recycling stage

[0054]

[0055] Life cycle inventory phase

[0056] The impact of the distribution network transformer's full life cycle on carbon emissions mainly includes factors such as raw materials and energy consumption. The raw materials mainly include metal ores, oil, natural gas, and coal. Greenhouse gases mainly include carbon dioxide. The transformer's waste recycling stage provides effective gains for reducing carbon emissions, is beneficial to environmental protection, and reduces the energy and raw material consumption of the distribution network transformer throughout its life cycle. The life cycle list of the distribution network transformer is shown in Table 6:

[0057] Table 6 Distribution network transformer life cycle list

[0058]

[0059] Furthermore, the transformer described in the present invention is an oil-immersed distribution network transformer.

[0060] Compared with the prior art, the beneficial effects of the present invention are:

[0061] Based on the carbon footprint analysis method of distribution network transformers for life cycle assessment, the present invention takes oil-immersed distribution network transformers as the research object, conducts research on carbon emissions throughout the life cycle, obtains the total carbon emissions during the life cycle, and further explores the carbon emissions at each stage of the life cycle. The total carbon emissions of distribution network transformers are 112178kg. The operation stage is the main stage of carbon emissions, accounting for 99.03% of the total carbon emissions, the carbon emissions in the production stage account for 0.25%, the carbon emissions in the transportation and construction and installation stages account for 0.7% and 0.11% respectively, and the carbon emissions in the waste recycling stage account for the least -0.09%. Through the sensitivity of transformer silicon steel sheets, it is known that silicon steel sheets have a significant impact on the carbon emissions of distribution network transformers during their life cycle. The higher the grade of silicon steel sheets, the lower their carbon emissions. From an overall analysis, the key to reducing carbon emissions throughout the life cycle is to improve the corresponding technology. The most critical factor is to improve the process in the production and manufacturing process and adopt more energy-saving and efficient devices to more effectively reduce the carbon emissions and total energy requirements of distribution network transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 Transformer 3D model diagram;

[0063] Figure 2 The national distribution transformer market share structure in 2023;

[0064] Figure 3 Distribution network transformer system accounting boundary;

[0065] Figure 4 Flow chart of green disassembly and recycling of distribution network transformers;

[0066] Figure 5 Distribution of carbon footprint of transformers in distribution networks;

[0067] Figure 6 The composition of the carbon footprint of distribution network transformers;

[0068] Figure 7 Energy requirements at all stages of the distribution network transformer life cycle;

[0069] Figure 8 Sensitivity analysis of silicon steel sheet models for distribution network transformers. DETAILED DESCRIPTION

[0070] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0071] like Figure 1-8 As shown,

[0072] Experimental example: Carbon footprint analysis method of distribution network transformer based on life cycle assessment,

[0073] Research Method and Data Acquisition of Carbon Footprint of Distribution Network Transformers

[0074] Determination of research objectives and scope

[0075] Research objectives

[0076] At present, my country's 10kV distribution network transformers are mainly divided into oil-immersed and dry-type transformers. Oil-immersed transformers are mostly used in urban and rural distribution networks. In 2023, the proportion of distribution network transformers is as high as 89.66%. Based on this, oil-immersed transformers are selected as the research object. The proportion structure of oil-immersed transformers is as follows: Figure 2 As shown:

[0077] In order to evaluate the impact of the distribution network transformer on the environment during its entire life cycle, the carbon footprint distribution of each component of the distribution network transformer from "cradle" to "grave" is analyzed. This paper takes 10kV distribution network transformer as the research object, and conducts carbon footprint analysis and measurement of the entire life cycle from the five stages of product production and assembly, transportation, installation, operation, and recycling.

[0078] Carbon Footprint System Boundary

[0079] The present invention establishes the accounting boundary of the distribution network transformer. The whole life cycle of the distribution network transformer includes the raw material acquisition stage, production and assembly stage, transportation stage, construction and installation stage, operation and use stage, and recycling and processing stage. According to the whole life cycle method, the accounting boundary is determined from "cradle to grave". Figure 3 shown.

[0080] Distribution Network Transformer Life Cycle Inventory Data

[0081] Production stage

[0082] The production stage of distribution network transformers mainly involves the consumption of materials and energy, which will generate a large amount of carbon emissions. The carbon emissions in the production and manufacturing stage of distribution network transformers mainly include carbon emissions from raw material acquisition, production and assembly, including carbon emissions in the production and assembly process of steel plates, copper wires, silicon steel sheets, transformer oil, etc. The data of other components are difficult to obtain. Therefore, only the carbon emissions of the above components are considered in the production stage. The carbon emission calculation formula for the production stage of distribution network transformers is as follows:

[0083]

[0084] Where, CF productionis the carbon emission during the production of distribution network transformers, CF production·n They represent the carbon emissions of steel plates, copper wires, silicon steel sheets and transformer oil respectively. The carbon emission coefficients in the production and assembly stage are shown in Table 2:

[0085] Table 2 Carbon emission coefficients in the production and assembly stage

[0086]

[0087] Transportation Stage

[0088] The transportation method of the raw materials, components and complete equipment of the distribution network transformer is mostly road transportation. The carbon dioxide produced per ton / kilometer of road transportation is 0.23kg, and the total energy required is 2.66M. The present invention estimates the transportation distance based on relevant research and reference. The comprehensive transportation distance of its materials is about 900km. The carbon emission calculation formula in the transportation stage is as follows:

[0089] CF transport =∑M×D i ×Ene per ×0.372 (2)

[0090] Where, CF transport is the carbon emission in the transportation stage; M is the weight of the distribution network transformer; D i is the transportation distance; per is the unit energy consumption of the transportation mode; 0.372 represents the carbon emission coefficient of gasoline and diesel. The carbon emission coefficient in the transportation stage is shown in Table 3:

[0091] Table 3 Carbon emission coefficients in the transportation stage

[0092]

[0093] Operational stage

[0094] According to the technical specification for the solidification of standardized materials for distribution networks issued by the State Grid Corporation of China headquarters, the life of distribution network transformers should be no less than 40 years. In the present invention, the service life is calculated as 40 years, and the annual operating time is generally 8760 hours. In the process of calculating carbon emissions, the power loss of the transformer is a key factor. Based on this, the calculation formula for the power loss of the transformer is given:

[0095]

[0096] In the formula, △A is the power loss, △P c is the transformer short-circuit loss, S is the transformer through capacity, S c is the rated capacity of the transformer, τ is the loss hours, △P0 is the no-load loss of the transformer, and T is the annual operating time of the transformer.

[0097] The operation phase of the distribution network transformer is the main phase of carbon emissions in the entire life cycle, accounting for more than 90%, which is much larger than the operation and maintenance of the equipment and the replacement of parts. Therefore, the carbon emissions in the transformer operation phase are processed as follows: the distribution network transformer has a service life of 40 years, and the annual operation time is 8760h. The power loss of the transformer is calculated to be 208720kWh. The carbon emission calculation formula for the operation phase of the distribution network transformer is as follows:

[0098] CF run =△A×Ene electricity (4)

[0099] Where, CF run Ene is the carbon emission in the operation phase; electricity is the carbon emission coefficient of electricity. The carbon emission coefficients in the operation stage are shown in Table 4.

[0100] Table 4 Carbon emission coefficients during operation

[0101]

[0102] Waste recycling stage

[0103] At present, the recycling of transformers in my country's distribution network is mainly carried out through the unified auction of the State Grid and small batch processing by user enterprises.

[0104] The recycling and disassembly level is relatively extensive and cannot reach the level of green

[0105] The present invention refers to the recycling of power distribution network transformers at home and abroad for discussion and analysis. The process adopts a green disassembly and recycling method. The process is as follows: Figure 4 As shown:

[0106] The structure of distribution network transformers is basically the same, and the recycled materials are also the same, mainly including silicon steel sheets, copper, aluminum and insulating oil, and the remaining materials are disposed of as municipal solid waste landfill. The carbon emission calculation formula for the waste recycling stage of distribution network transformers is as follows:

[0107] CF recycling =∑M×Ene m·per ×Ene n·energy (5)

[0108] Where, CF transport is the carbon emission in the transportation stage; M is the weight of the distribution network transformer; Ene m·per Ene is the unit energy consumption of waste treatment; n·energy is the carbon emission coefficient of waste treatment. The carbon emission coefficient in the waste recycling stage is shown in Table 5:

[0109] Table 5 Carbon emission coefficients in the waste recycling stage

[0110]

[0111] Life cycle inventory phase

[0112] The impact of the distribution network transformer's full life cycle on carbon emissions mainly includes factors such as raw materials and energy consumption. The raw materials mainly include metal ores, oil, natural gas, and coal. Greenhouse gases mainly include carbon dioxide. The transformer's waste recycling stage provides effective gains for reducing carbon emissions, is beneficial to environmental protection, and reduces the energy and raw material consumption of the distribution network transformer throughout its life cycle. The life cycle list of the distribution network transformer is shown in Table 6:

[0113] Table 6 Distribution network transformer life cycle list

[0114]

[0115] Research Results and Analysis

[0116] Carbon Footprint Analysis of Distribution Network Transformers

[0117] The carbon footprint of distribution network transformers at each stage of their life cycle is as follows: Figure 5 As shown in the figure, it can be seen that the total carbon emissions during the life cycle are 112178kg, and the carbon emissions in the operation stage are 111079.64kg, which accounts for the largest proportion in the entire cycle, accounting for 99.03%; the carbon emissions in the production stage are 282kg, accounting for 0.25%; the carbon emissions in the transportation stage are 782kg, accounting for 0.7%; the carbon emissions in the construction and installation stage are 122.96kg, accounting for 0.11%; the carbon emissions in the recycling and processing stage are -88.6kg, because the recycling of distribution network transformer materials can effectively replace the impact of transformer raw material mining and production processes on the environment, which is conducive to reducing carbon emissions. Therefore, the carbon emissions in the recycling and processing stage are negative.

[0118] The production of various parts of distribution network transformers will have corresponding carbon emissions. The carbon emissions generated by different parts are different. Figure 6 The carbon footprint output of each component is given in the figure. It can be seen from the figure that the production of copper wire has the largest output in carbon emissions, accounting for 30%, followed by the production process of silicon steel sheets, accounting for 24% of the carbon emissions in the production process, and then copper foil, accounting for 16%, which is much larger than the carbon emissions generated in the production of core clips, paperboard and copper bars. Therefore, improving the production process of copper wire, silicon steel sheets, copper foil, transformer oil and copper plates can effectively reduce the consumption of raw materials and energy, reduce carbon emissions and increase environmental friendliness.

[0119] The carbon emissions of distribution network transformers during the transportation stage mainly come from the energy consumption of vehicles during operation, mainly including the consumption of gasoline and diesel by vehicles; the carbon emissions during the construction and installation stage come from the energy consumption of engineering vehicles and the electricity consumption during the installation process, and the carbon emissions generated are 782kg. The operation stage of distribution network transformers is the stage with the highest proportion of carbon emissions in the entire life cycle. This is because there are many losses generated during operation (load losses, no-load losses). The large amount of electricity loss during long-term operation is a key factor in the generation of carbon emissions. The carbon emissions of transformers during the entire operation stage are approximately 111079.64kg. The waste recycling stage of distribution network transformers mainly includes their disassembly and recycling of major components. The disassembly will consume corresponding electricity and generate corresponding carbon emissions, but the recycling of materials will also reduce the carbon emissions generated by transformers in production and manufacturing. The combined carbon emissions are -88.6kg. Analysis of total energy demand in the life cycle of distribution network transformers

[0120] Distribution network transformers consume corresponding energy at various stages in their life cycle. The total energy demand in their life cycle is Figure 7 It is given in the figure that the total energy demand of the distribution network transformer is 798.21GJ. Among the five stages, the energy demand in the operation stage is the highest, which is 785.97GJ, accounting for 98.47%; the energy demand in the production stage is 2.12GJ, accounting for 0.27%; the energy demand in the transportation stage is 9.06GJ, accounting for 1.13%; the energy demand in the construction and installation stage is 1.34GJ, accounting for 0.17%; the energy demand in the waste recycling stage is -0.28GJ, and it is found that its value is negative, mainly because the waste recycling stage produces better environmental benefits, which is of great help to energy conservation and emission reduction.

[0121] Sensitivity analysis of transformers in distribution networks

[0122] The present invention analyzes that the carbon emissions of distribution network transformers are the highest during the operation stage of their entire life cycle. The key factor affecting their carbon emissions is the efficiency of the transformer, and improving efficiency can be achieved by improving the material. Silicon steel sheets are the core raw material for controlling the loss of distribution network transformers. In order to explore the impact of silicon steel sheets on carbon emissions, it is necessary to conduct a sensitivity analysis of silicon steel sheets for distribution network transformers. In the production process of distribution network transformers, other materials are kept unchanged, and the material of silicon steel sheets is changed. Three models of B30P105, B20R070, and B23R070 are used respectively to obtain the following: Figure 8The sensitivity analysis diagram is shown. The silicon steel sheet model B30P105 of the present invention is the benchmark value. With the application of high-grade silicon steel sheets, the carbon emissions are continuously reduced. It can be seen from the figure that the carbon emissions of B20R070 and B23R070 silicon steel sheets are reduced by 11.7% and 11.9% respectively. Through analysis, it is known that the silicon steel sheet of the distribution network transformer is a key factor affecting carbon emissions.

[0123] Low-carbon strategy for distribution network transformers in the entire life cycle

[0124] In order to effectively reduce the carbon emissions of the power system, the distribution network transformer, as a key power equipment in the transmission and distribution system, plays a key role in the carbon reduction process. In the entire life cycle of the distribution network transformer, corresponding greenhouse gases are generated at each stage. Through the analysis of carbon emissions at each stage, the corresponding measures for energy conservation and emission reduction at each stage are determined. In the production stage, the mining process of raw materials and the manufacturing process can be improved to reduce carbon emissions; in the transportation stage, new energy vehicles can be used for transportation; in the construction and installation stage, energy-saving and efficient construction technology is adopted to improve the construction efficiency of workers; in the operation stage, the inspection and maintenance of the transformer is strengthened, and the transformer ratio is reasonably adjusted; in the recycling and processing stage, green disassembly methods are adopted to improve the recycling rate of products.

[0125] In * month of 20**, Wang Yanpeng et al.: Carbon footprint analysis of distribution network transformer based on life cycle assessment 4 This invention takes oil-immersed distribution network transformer as the research object, conducts research on carbon emissions in the whole life cycle, obtains the total carbon emissions in the life cycle, and further explores the carbon emissions in each stage of the life cycle. The total carbon emissions of the distribution network transformer are 112178kg. The operation stage is the main stage of carbon emissions, accounting for 99.03% of the total carbon emissions. The carbon emissions in the production stage account for 0.25%, and the carbon emissions in the transportation and construction and installation stages account for 0.7% and 0.11% respectively. The carbon emissions in the waste recycling stage account for the least -0.09%. Through the sensitivity of the transformer silicon steel sheet, it is known that the silicon steel sheet has a significant impact on the carbon emissions of the distribution network transformer life cycle. The higher the grade of silicon steel sheet, the lower its carbon emissions. From the overall analysis, the key to reducing carbon emissions in the whole life cycle is to improve the corresponding technology. The most critical factor is to improve the process in the production and manufacturing process and adopt more energy-saving and efficient devices to more effectively reduce the carbon emissions and total energy requirements of the distribution network transformer.

[0126] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that are not conceived through creative work should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. A carbon footprint analysis method for distribution network transformers based on life cycle assessment, characterized by: It consists of the following steps: Step 1: Determine the carbon footprint system boundary Establish accounting boundaries for distribution network transformers. The full life cycle of distribution network transformers includes the raw material acquisition stage, production and assembly stage, transportation stage, construction and installation stage, operation and use stage, and recycling and disposal stage. Based on the full life cycle approach, the accounting boundary is determined from "cradle to grave"; Step 2: Determine the life cycle inventory data of distribution network transformers at different stages Production stage The carbon emissions during the production phase are based on the production and assembly of steel plates, copper wires, silicon steel sheets, and transformer oil. The carbon emissions calculation formula for the fourth stage of the distribution network transformer production is as follows: Where, CF production is the carbon emissions from the production of distribution network transformers, CF production·n Represent the carbon emissions of steel plates, copper wires, silicon steel sheets, and transformer oil respectively; the carbon emission coefficients during the production and assembly stages are as follows: Transportation stage The transportation method for raw materials, components, and complete equipment of distribution network transformers is mostly road transportation. Road transportation produces 0.23kg of carbon dioxide per ton / kilometer and requires a total energy of 2.66MJ. The comprehensive transportation distance of the materials is calculated as 900km. The carbon emissions calculation formula during the transportation stage is as follows: CF transport =∑M×D i ×Ene per ×0.372 (2) Where, CF transport is the carbon emission in the transportation stage; M is the weight of the distribution network transformer; Di is the transportation distance; Ene per is the unit energy consumption of the transport mode; 0.372 represents the carbon emission coefficient of gasoline and diesel; the carbon emission coefficients in the transport stage are as follows: Carbon emission coefficient during transportation Operational phase The service life is calculated as 40 years, and the annual operating time is generally 8760 hours. The power loss of the transformer is a key factor in the calculation of carbon emissions. Based on this, the calculation formula for the power loss of the transformer is given: In the formula, △A is the power loss, △P c is the transformer short-circuit loss, S is the transformer through capacity, S c is the rated capacity of the transformer, τ is the loss hours, △P0 is the no-load loss of the transformer, and T is the annual operating time of the transformer; The operation phase of a distribution network transformer is the primary source of carbon emissions throughout its lifecycle, accounting for over 90% and significantly greater than equipment maintenance, overhaul, and component replacement. Therefore, the carbon emissions during the transformer operation phase are calculated as follows: Assuming a 40-year service life and 8,760 hours of operation per year, the transformer's power loss is calculated to be 208,720 kWh. The formula for calculating carbon emissions during the operation phase of a distribution network transformer is as follows: CF run =△A×Ene electricity (4) Where, CF run Ene is the carbon emission during the operation phase; electricity is the carbon emission coefficient of electricity; the carbon emission coefficient during the operation phase is as follows; Carbon emissions during operation Waste recycling and processing stage At present, the recycling of transformers in my country's distribution network is mainly carried out through the State Grid's unified auction and small batch processing by user enterprises. The recycling and disassembly level is relatively extensive and cannot reach the level of green Low carbon, low carbon and environmentally friendly level; The process adopts the green disassembly and recycling method, and the process is as follows: ①: State Grid Corporation of China recycles retired transformers; ②: Rely on recycling manufacturers to carry out green dismantling of transformers to extract transformer oil, silicon steel sheets, copper, aluminum and other metal materials; ③: The extracted metal materials are processed by metal smelting enterprises; ④: The metal materials extracted by metal smelting enterprises are reused by transformer manufacturers, and at the same time, the dismantled transformer oil is also reused by transformer manufacturers; ⑤: Transformer manufacturers use recycled materials to produce new transformers; Recycled materials include silicon steel sheets, copper, aluminum, and insulating oil. The remaining materials are disposed of as municipal solid waste landfills. The carbon emissions calculation formula for the waste recycling and treatment stage of distribution network transformers is as follows: CF recycling =∑M×Ene m·per ×Ene n·energy (5) Where, CF transport is the carbon emission in the transportation stage; M is the weight of the distribution network transformer; Ene m·per Ene is the unit energy consumption of waste treatment; n·energy The carbon emission coefficient for waste treatment is as follows: Carbon emission coefficient in the waste recycling and treatment stage Life cycle inventory stage The impact of the distribution network transformer's full life cycle on carbon emissions mainly includes factors such as raw materials and energy consumption. Raw materials mainly include metal ores, oil, natural gas, and coal; greenhouse gases mainly include carbon dioxide. The transformer's waste recycling stage provides effective benefits for reducing carbon emissions, which is beneficial to environmental protection and reduces energy and raw material consumption throughout the distribution network transformer's full life cycle. The distribution network transformer life cycle list is as follows: Distribution Network Transformer Life Cycle Inventory 2. The method according to claim 1 is characterized in that The transformer is an oil-immersed distribution network transformer.

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