Source network carbon-loaded emission reduction accounting method in operation stage of extra-high voltage power delivery project

Abstract

The invention discloses a source network carbon-loaded emission reduction accounting method in an operation stage of an extra-high voltage power delivery project, and the method comprises the following specific steps: 1, determining the type of the extra-high voltage power delivery project, judging whether the extra-high voltage power delivery project is connected to a new energy power plant or not, and undertaking a new energy transmission task; the extra-high-voltage project is divided into an extra-high-voltage project undertaking a new energy transmission task and an extra-high-voltage project not undertaking the new energy transmission task; based on engineering types, respectively defining carbon emission reduction accounting ranges of a power generation side, a power grid side and a load side; and 2, based on the accounting ranges of the power generation side, the power grid side and the load side, the carbon emission reduction amount of the extra-high voltage power delivery project is determined, and the whole-process accounting of the carbon emission reduction in the operation stage of the extra-high voltage project is realized. According to the source network carbon-loaded emission reduction accounting method in the operation stage of the extra-high-voltage power delivery project, measurement and calculation are carried out from the power generation side, the load side and the power grid side respectively, measurement and calculation of carbon emission reduction of the extra-high-voltage project are achieved, and carbon emission reduction benefits generated by new energy consumption are reasonably distributed.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon emission accounting methods for power systems, and specifically relates to a method for calculating carbon emission reductions in sources, grids and loads during the operation phase of ultra-high voltage power transmission projects. Background Art

[0002] The power industry is a major source of carbon emissions. To address the mismatch between regional electricity demand and power generation, China has increased the construction of ultra-high voltage (UHV) projects, primarily designed to mobilize electricity across long distances. These projects effectively connect power load centers with power energy production sites. UHV transmission projects offer low energy consumption and minimal environmental impact, making them efficient transmission channels for green electricity. The International Greenhouse Gas Protocol (IGP) categorizes carbon emissions into direct and indirect emissions. Existing research and analysis of direct and indirect carbon emissions from power systems includes methods for analyzing direct carbon emissions, including fuel emission factors, material balances, and field measurements. Regarding indirect carbon emissions, scholars have developed and proposed methods for measuring and analyzing indirect carbon emissions from power systems, including grid emission factors, sensitivity tracking, cooperative game theory, pricing mechanisms, and carbon emission flow tracking, based on different allocation principles. In addition to the commonly used methods mentioned above, a refined, full-process carbon measurement method based on carbon emission flow theory has been proposed. This method enables real-time, minute-by-minute carbon measurement of electricity carbon information across the power system's source, grid, and load sides, as well as refined, user-level carbon measurement. However, this method lacks provincial-level sharing of the low-carbon benefits of clean energy and places high demands on data. Power systems have different voltage levels. For EHV / UHV levels within the transmission network, standards such as IEC 60038 (standard voltage values), IEC 60071 (insulation coordination), and IEC 62271 (switchgear) should be referenced. It is generally accepted that AC 1000 kV and above or DC ±800 kV and above are UHV. Although UHV transmission lines are part of the power system, the impact of voltage level differences on carbon emission accounting requires a clear understanding of the unique characteristics of UHV projects compared to conventional transmission systems, as well as the different accounting method requirements. While the aforementioned methods for power system carbon emission accounting can also be applied to UHV lines, they are not highly specific. There are few existing studies on the accounting and measurement of carbon emissions from UHV projects, and most of them are analyzed from the perspective of the entire life cycle, calculating the carbon emissions from the construction stage to the final recovery stage.

[0003] At present, the traditional power system carbon emission accounting method has the following problems: (1) There are a lot of research results on power system carbon emission accounting, but it faces a significant adaptability bottleneck in UHV projects. Although the traditional power system carbon emission accounting method can follow its basic framework, in the UHV scenario, it must additionally consider key factors such as the extension effect of the transmission space scale, the performance differences brought about by the technology generation change, and the emission deviation caused by the doubling of the SF6 gas density in the high-voltage equipment. Therefore, it is difficult to apply directly and needs further optimization and expansion. (2) From the perspective of the whole life cycle, existing research focuses on the carbon emission accounting of the project construction phase, while the project operation phase is often simplistic and one-sided; however, in the power system, the operation phase not only lasts for a long time and has a wide range of impact, but is also the core link of carbon emissions. Therefore, it is urgent to strengthen the detailed quantification and dynamic tracking of its operation process in the method system to accurately reveal the substantial contribution of the grid operation to the overall carbon footprint. (3) Limited analysis of the synergistic effects of various components: The carbon emission accounting of UHV projects during the operation phase is still insufficient, and there is a lack of detailed analysis of transmission lines, substations, control systems, etc. In addition, an effective model has not yet been established to accurately quantify the laws of carbon emissions during the operation of the project under the synergistic effects of source, grid, load and storage. This lack of analysis limits the comprehensive understanding of the dynamics of carbon emissions during the operation of UHV projects and is not conducive to the formulation of targeted emission reduction strategies. (4) Lack of deep integration with the power system: A carbon emission reduction assessment framework that is deeply integrated with the power system has not yet been established. (5) The lack of such an assessment system makes it difficult to quantify the carbon reduction contribution of UHV projects in the overall power system. The interaction mechanism of carbon emission transfer is imperfect: In the process of new energy consumption, UHV projects play an important role in cross-regional power balance. However, existing research has failed to deeply reveal the interaction mechanism between cross-regional power balance and carbon emission transfer. For example, the transmission of clean energy to the load center through UHV lines may lead to the redistribution of carbon emissions in the sending and receiving areas. The lack of a deep understanding of this transfer mechanism may lead to unclear division of carbon emission responsibilities and affect the coordinated emission reduction between regions. (6) Existing research cannot clearly define the role of UHV power transmission projects in absorbing new energy and reducing carbon dioxide emissions during their operation phase.

[0004] To sum up, the full-process carbon emission reduction accounting system for the operation phase of ultra-high voltage transmission projects proposed based on the calculation method of power system carbon emissions can reasonably and accurately allocate the carbon emission reduction benefits brought by the consumption of new energy to the power generation side, grid side, and load side. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for calculating carbon emission reduction from source, grid and load during the operation phase of ultra-high voltage power transmission projects. The method realizes the measurement of carbon emission reduction of ultra-high voltage projects by measuring from the power generation side, load side and grid side respectively, and reasonably distributes the carbon emission reduction benefits generated by the consumption of new energy.

[0006] The technical solution adopted by the present invention is a method for calculating carbon emission reductions in the source, grid and load during the operation phase of an ultra-high voltage power transmission project, which is specifically implemented in the following steps: Step 1: Determine the type of UHV power transmission project and whether it is connected to a renewable energy power plant and undertakes renewable energy transmission tasks. These projects are categorized as UHV projects that undertake renewable energy transmission tasks and those that do not. Based on the project type, define the carbon emission reduction accounting scope for the power generation side, the grid side, and the load side. Step 2: Based on the accounting scope of the power generation side, grid side and load side, determine the carbon emission reduction of the UHV power transmission project, and realize the full-process accounting of carbon emission reduction during the operation phase of the UHV project.

[0007] The technical solution of the present invention is also characterized in that: The specific accounting scope of the power generation side of the UHV project that undertakes the task of transmitting new energy in step 1 is: Assuming that after the establishment of the UHV power transmission project, the proportion of fossil energy in the power transmitted by each power plant is: , ,…, , the local load power supply of each power plant is , ,…… , from which we can get the proportion of fossil energy electricity in the total electricity on the power generation side of a certain UHV power transmission project for: (1) Where n is the number of power plants; The proportion of non-fossil energy electricity in the total electricity for: (2) Assume that before the project is built, the proportion of fossil energy in the electricity delivered by each power plant is , ,…, , and the corresponding average fossil energy electricity is obtained Proportion and average non-fossil energy electricity proportion , the carbon emission reduction on the power generation side can be obtained, as shown in formula (5): (3) (4) (5) Where, is the carbon emission reduction on the power generation side, is the difference in the average proportion of fossil energy electricity before and after the construction of the UHV power transmission project. The power supply amount of the power generation side to the users in the area, is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal, where The amount of electricity supplied to the local load of each power plant, i ranges from 1 to n.

[0008] The specific calculation scope of the grid side of the UHV project that undertakes the task of transmitting new energy in step 1 is: UHV transmission projects require supporting large-capacity converter stations or substations. The amount of SF6 contained in the equipment increases significantly, and its leakage leads to direct carbon emissions. For this part of the direct carbon emissions on the grid side, first of all, the leakage of SF6 gas takes into account the emissions generated during the equipment repair and decommissioning process. Therefore, the increase in direct carbon emissions on the grid side of the UHV power transmission project is the emissions generated by the additional SF6-containing equipment required to realize the power transmission and distribution of the project after the construction of the power transmission project. The calculation method is formula (6), specifically: (6) Where, and They represent the sulfur hexafluoride capacity on the nameplates of the newly added decommissioned equipment and repaired equipment containing sulfur hexafluoride in the UHV project; and Represent the actual recovery amount of sulfur hexafluoride of retired equipment and repaired equipment respectively; Secondly, assuming that the loss ratio of fossil energy power and non-fossil energy power during transmission is the same, for the increased carbon emissions in the transmission and distribution process after the construction of the UHV power transmission project, since non-fossil energy power is not included in the carbon emissions, the proportion of non-fossil energy power in the transmitted power is obtained, that is, the indirect carbon emissions caused by the loss of fossil energy power are calculated according to formula (8): (8) Where, Carbon emissions caused by power loss during the transmission and distribution of UHV power transmission projects; is the energy loss during transmission and distribution, MWh; is the annual average power supply emission factor of the regional power grid, t CO2 / MWh; The proportion of fossil energy in the electricity delivered; When calculating the increase in carbon emissions on the grid side, and Overlay value.

[0009] The emissions generated by SF6-containing equipment are calculated using the average fugitive emission method. According to formula (7), the direct carbon emissions generated by sulfur hexafluoride equipment are calculated as follows: (7) Where, for Emission factors; For the Taiwan Sulfur hexafluoride capacity on the equipment nameplate, kg; for Annual gas leakage rate, including Average annual gas leakage rate Take 0.5%, Take 25184t CO2 / t.

[0010] The load-side accounting scope of the UHV project that undertakes the task of transmitting new energy in step 1 is as follows: first, calculate the difference between the power transmission of a certain UHV power transmission project in a certain year and the proportion of non-fossil energy power generation in the load area, then obtain the power transmission of the UHV power transmission project, calculate the reduced power generation of coal-fired power generation in the load area, and finally obtain the carbon emission reduction caused by the UHV project in the area through the carbon emission factor; assuming that the loss ratio of fossil energy power and non-fossil energy power during transmission is the same, then the proportion of fossil energy power and non-fossil energy power in the power transmission process and the power transmission to the load side are the same; specifically, as shown in formula (9): (9) Where, is the carbon emission reduction in the load area; The proportion of non-fossil energy in the total electricity delivered for the UHV power transmission project; The proportion of non-fossil energy in the total electricity consumed in the load area when the project is not connected; Transmit electricity for the UHV power transmission project; is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal.

[0011] The carbon emission reductions of UHV projects that undertake new energy transmission tasks are as follows: (10) Where, is the carbon emission reduction on the power generation side, is the increase in carbon emissions on the grid side, It is the carbon emission reduction on the load side.

[0012] The specific accounting scope of the power generation side of the UHV project without the new energy transmission task in step 1 is: This type of UHV power transmission project is not connected to a new energy power plant, and the power it transmits is all fossil energy power. 1, the proportion of non-fossil energy electricity is 0, specifically: (11) (12) (13) Where, is the carbon emission reduction on the power generation side, is the difference in the average proportion of fossil energy electricity before and after the construction of the UHV power transmission project. The power supply amount of the power generation side to the users in the area, is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal, n is the number of power plants, where The amount of electricity supplied to the local load of each power plant, i ranges from 1 to n.

[0013] The specific calculation scope of the grid side of the UHV project without the new energy transmission task in step 1 is: Calculate the direct carbon emissions generated by SF6 equipment and the indirect carbon emissions generated by line losses, taking into account the proportion of non-fossil energy in the transmitted electricity. is 0, =1, calculated according to formula (14), specifically: (14) Where, Carbon emissions caused by power loss during the transmission and distribution of UHV power transmission projects; is the power loss during transmission and distribution, MWh; is the annual average power supply emission factor of the regional power grid, t CO2 / MWh; Then, the increase in carbon emissions on the grid side is: (15) Where, As carbon emissions on the grid side increase, Direct carbon emissions caused by SF6 gas leakage, Carbon emissions caused by power loss during the transmission and distribution of UHV power transmission projects.

[0014] The load-side accounting scope of UHV projects that do not undertake new energy transmission tasks in step 1 is specifically as follows: (16) Where, is the increase in carbon emissions for that load area; The proportion of fossil energy in the total electricity consumed in the load area when the project is not connected; Transmit electricity for the UHV power transmission project; is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal.

[0015] The carbon emission reductions of UHV projects that do not undertake new energy transmission tasks are as follows: (17) Where, For carbon emissions from power generation, is the increase in carbon emissions on the grid side, It is the carbon emission on the load side.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The method for calculating carbon emission reductions from sources, grids, and loads during the operation phase of UHV power transmission projects provided by this invention covers different regions during the operation phase of UHV power transmission projects and takes into account the differences in carbon metering in each region. It also provides support for the precise tracing and responsibility allocation of carbon emissions from cross-regional power transmission projects under the background of new power systems. It also comprehensively considers the operating characteristics of the power generation side, grid side, and load side that maintain a high degree of linkage and dynamic balance in time and space, and accurately quantifies the evolution of the carbon footprint under the synergy of sources, grids, loads, and storage during the operation of the project.

[0017] (2) The present invention provides a method for calculating carbon emission reductions across the source, grid, and load of UHV power transmission projects during their operation phase. Different calculation models are proposed for calculating the carbon emission reduction benefits on the generation, load, and grid sides of UHV power transmission projects. These calculations accurately measure the carbon emission reductions of UHV projects from three perspectives and rationally allocate the carbon emission reduction benefits generated by the consumption of new energy. Unlike carbon emission accounting from a full life cycle perspective, which focuses on the construction phase and ignores the construction and recovery phases, this method establishes a carbon emission reduction assessment framework that is deeply integrated with the power system during the UHV project operation phase.

[0018] (3) The method for calculating carbon emission reductions between the source, grid and load during the operation phase of the UHV power transmission project provided by the present invention can serve as an algorithmic support for the UHV power transmission project in promoting the absorption of new energy and reducing carbon dioxide emissions, and can be used to quantitatively analyze its carbon emission reduction potential with the help of empirical calculation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of the method for calculating carbon emission reductions in the source, grid, and load during the operation phase of an ultra-high voltage power transmission project according to the present invention; Figure 2 Schematic diagram of the process of grid-side carbon emissions in the present invention; Figure 3 This is a topological diagram of the UHV power transmission project case in Example 6; Figure 4 This is a comparison chart of carbon emission reductions for each transmission channel from 2022 to 2023 in Example 6; Figure 5 This is a schematic diagram of carbon emission reduction on each side of the Lugu ±800kV DC transmission project in Example 6; Figure 6 This is a schematic diagram of carbon emission reduction on each side of the Mengxi-Tianjin South 1000kV UHV AC project in Example 6; Figure 7 It is the carbon emission reduction on each side of the Ximeng-Shandong 1000kV UHV AC project in Example 6. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 The present invention provides a method for calculating carbon emission reduction in the source, grid and load during the operation phase of UHV power transmission projects. Figure 1-2 The specific steps are as follows: Step 1: Determine the type of UHV power transmission project and whether it is connected to a renewable energy power plant and undertakes renewable energy transmission tasks. These projects are categorized as UHV projects that undertake renewable energy transmission tasks and those that do not. Based on the project type, define the carbon emission reduction accounting scope for the power generation side, the grid side, and the load side. Step 2: Based on the accounting scope of the power generation side, grid side and load side, determine the carbon emission reduction of the UHV power transmission project, and realize the full-process accounting of carbon emission reduction during the operation phase of the UHV project.

[0022] Example 2 On the basis of Example 1, in order to calculate the carbon emissions on the power generation side, grid side, and load side of the UHV power transmission project that undertakes the task of transmitting new energy, the present invention constructs the following Figure 1 The full-process carbon emission reduction accounting system for the operation phase is shown. The calculation of this accounting system includes the following steps: 1. Power generation side Due to the optimization of regional power resource allocation, line failures and other reasons, these supporting and existing power plants transmit the power that should have been transmitted to the load side to the local load. Assuming that after the project is established, the proportion of fossil energy power in the power transmitted by each power plant is: , ,…… , the local load power supply of these power plants is , ,…… From this, we can get the proportion of fossil energy power in the total power on the power generation side of a certain UHV power transmission project. for: (1) The proportion of non-fossil energy electricity in the total electricity for: (2) Assume that before the project is built, the proportion of fossil energy in the electricity delivered by each power plant is: , ,…… , the corresponding average fossil energy electricity can also be calculated Proportion and average non-fossil energy electricity proportion , the carbon emission reduction on the power generation side can be obtained as shown in the following formula (5): (3) (4) (5) Where, is the carbon emission reduction on the power generation side, is the difference in the average proportion of fossil energy electricity before and after the construction of the UHV power transmission project. The power supply amount of the power generation side to the users in the area, is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal, where The amount of electricity supplied to the local load of each power plant, i ranges from 1 to n.

[0023] Example 3 Based on Example 2, 2. Grid side UHV transmission projects require supporting large-capacity converter stations / substations. The amount of sulfur hexafluoride (SF6) contained in GIS and other equipment has increased significantly, and its leakage has brought direct carbon emissions. For this part of the direct carbon emissions on the grid side, the present invention first analyzes the direct carbon emissions caused by SF6 gas leakage. SF6 gas has very excellent insulation properties and is widely used as an insulating medium in power equipment. The leakage of SF6 gas in SF6-containing equipment of power grid enterprises has no direct relationship with the amount of electricity transmitted by the transmission line. The leakage of SF6 gas mainly considers the emissions generated during the equipment repair and decommissioning process. Therefore, the increase in direct carbon emissions on the grid side of the UHV power transmission project is the emissions generated by the additional SF6-containing equipment required to realize the power transmission and distribution of the project after the construction of the power transmission project. That is, the calculation method is formula (6): (6) Where, and They represent the sulfur hexafluoride capacity on the nameplates of the newly added decommissioned equipment and repaired equipment containing sulfur hexafluoride in the UHV project; and They represent the actual recovery amounts of sulfur hexafluoride from retired equipment and repaired equipment respectively.

[0024] Alternatively, the average dissipation method can be used to calculate the direct carbon emissions from sulfur hexafluoride equipment according to formula (7). By incorporating actual data from the repair and decommissioning processes of sulfur hexafluoride equipment used by power grid companies each year, the direct carbon emissions from sulfur hexafluoride equipment can be accurately calculated. Alternatively, the average dissipation method can be used to calculate the direct carbon emissions from sulfur hexafluoride equipment according to the following formula (7): (7) Where, for Emission factors; For the Taiwan Sulfur hexafluoride capacity on the equipment nameplate, kg; for The annual leakage rate of gas. According to the relevant standards formulated by the country, Average annual gas leakage rate It can be taken as 0.5%, according to the data provided in the third part of the IPCC Sixth Assessment Report. Take 25184t CO2 / t.

[0025] Although UHV lines have an extremely low line loss rate, the power loss generated during large-scale, long-distance power transmission is still considerable, and the corresponding carbon emissions cannot be ignored. In this invention, it is also taken into account in the UHV carbon emission accounting system. Assuming that the loss ratio of fossil energy power and non-fossil energy power during transmission is the same, for the increased carbon emissions in the transmission and distribution process after the construction of the UHV power transmission project, since non-fossil energy power is not accounted for its carbon emissions, it is necessary to consider the proportion of non-fossil energy power in the transmitted power, that is, to calculate the indirect carbon emissions caused by the loss of fossil energy power, and calculate according to formula (8): (8) Where, Carbon emissions caused by power loss during the transmission and distribution of UHV power transmission projects; is the power loss during transmission and distribution, MWh; is the annual average power supply emission factor of the regional power grid, t CO2 / MWh; The proportion of fossil energy in the electricity transmitted.

[0026] When calculating the increase in carbon emissions on the grid side, and Overlay value.

[0027] Example 4 Based on Example 3, 3. Load side The calculation of load-side carbon emissions reductions primarily considers the shortfall in thermal power generation caused by the difference between the proportion of non-fossil energy in the total electricity consumed by the load region and the total electricity delivered by the UHV power transmission project. Since coal-fired power accounts for approximately 89% of China's thermal power generation, the increase in clean electricity consumption in the load region caused by UHV power transmission is roughly equivalent to the shortfall in coal-fired power generation in that region.

[0028] For load-side carbon emission reduction accounting, first, calculate the difference between the power transmission of a certain UHV power transmission project in a certain year and the proportion of non-fossil energy power generation in the load area. Then, obtain the operating data such as the power transmission of the UHV power transmission project, and calculate the reduction in coal-fired power generation in the load area. Finally, use the carbon emission factor to obtain the carbon emission reduction caused by this UHV project in the area.

[0029] Assuming that the loss ratio of fossil energy and non-fossil energy during transmission is the same, the proportion of fossil energy and non-fossil energy in the transmission process and the power transmitted to the load side are the same. The specific calculation formula is shown in formula (9): (9) Where, is the carbon emission reduction in the load area; The proportion of non-fossil energy in the total electricity delivered for the UHV power transmission project; The proportion of non-fossil energy in the total electricity consumed in the load area when the project is not connected; Transmit electricity for the UHV power transmission project; is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal.

[0030] Ultra-high voltage power transmission projects can better realize network interconnection, promote the consumption of new energy, increase the proportion of non-fossil energy electricity consumed in power generation areas and load areas, replace fossil energy electricity with non-fossil energy electricity, and ultimately achieve carbon emission reduction with the help of ultra-high voltage power transmission projects.

[0031] The carbon emission reductions from the UHV power transmission project are: (10) Where, is the carbon emission reduction on the power generation side, is the increase in carbon emissions on the grid side, is the carbon emission reduction on the load side, which is the coupled superposition value of the above embodiment.

[0032] Example 5 Based on Example 1, this example provides the calculation steps for UHV projects that do not undertake the task of transmitting new energy. Since such UHV power transmission projects are not connected to new energy power plants, the power they transmit is all fossil energy power. Therefore, the proportion of fossil energy power is 1, the proportion of non-fossil energy electricity is 0.

[0033] (11) (12) (13) Where, is the carbon emission reduction on the power generation side, is the difference in the average proportion of fossil energy electricity before and after the construction of the UHV power transmission project. The power supply amount of the power generation side to the users in the area, is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal, n is the number of power plants, where The amount of electricity supplied to the local load of each power plant, i ranges from 1 to n.

[0034] Refer to the calculation steps in Example 3 to calculate the direct carbon emissions generated by the sulfur hexafluoride equipment. For the indirect carbon emissions generated by line losses, it is necessary to consider the proportion of non-fossil energy in the transmitted electricity. is 0, =1, calculated according to formula (14): (14) Where, Carbon emissions caused by power loss during the transmission and distribution of UHV power transmission projects; is the power loss during transmission and distribution, MWh; is the average annual power supply emission factor of the regional power grid, t CO2 / MWh.

[0035] Then, the increase in carbon emissions on the grid side is also calculated separately from these two parts, namely: (15) In the formula As carbon emissions on the grid side increase, Direct carbon emissions caused by SF6 gas leakage, Carbon emissions caused by power loss during the transmission and distribution of UHV power transmission projects.

[0036] For the load side, the specific calculation formula is shown in formula (16): (16) Where, is the increase in carbon emissions for that load area; The proportion of fossil energy in the total electricity consumed in the load area when the project is not connected; Transmit electricity for the UHV power transmission project; is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal.

[0037] For the second category, they do not connect to new energy power plants and do not undertake new energy transmission tasks. They have no positive effect on carbon emission reduction benefits, and the increase in carbon emissions from their power transmission projects is: (17) Where, For carbon emissions from power generation, is the increase in carbon emissions on the grid side, It is the carbon emission on the load side.

[0038] Example 6 The feasibility of the solution in the above embodiment is verified by combining specific examples, as described below: Based on the installed capacity of a single unit in a thermal power plant and referring to the China Electric Power Statistical Yearbook, the standard coal consumption value of the power generation unit was selected; according to the "Guidelines for the Preparation of Provincial Greenhouse Gas Inventories", the carbon emission factor of standard coal was 2.66. According to the 6th IPCC announcement, the SF6 emission factor is 25184 tCO 2 / t According to GB / T 8905-2008 "Guidelines for the management and detection of sulfur hexafluoride gas in electrical equipment", the equipment The annual gas leakage rate must be ≤0.5%.

[0039] The number of converter stations / substations for UHV transmission lines is shown in Table 1 below, and the power transmission situation of typical cases of UHV transmission projects in 2022-2023 is shown in Table 2 below.

[0040] Table 1 Number of converter stations / substations for UHV transmission lines

[0041] Table 2 Typical cases of UHV transmission projects Power transmission in 2022-2023

[0042] The three lines mentioned above, namely the Lugu ±800kV DC transmission project, the Mengxi-Tianjin South 1000kV UHV AC project, and the Ximeng-Shandong 1000kV UHV AC project, were analyzed and the carbon emission reduction calculation results of each transmission channel are shown as follows: Figure 4 shown.

[0043] The Lugu DC and Ximeng-Shandong AC projects contribute positively to carbon emission reductions, while the Mengxi-Tianjin South project contributes negatively. Equations (5) and (9) show that the zero-renewable energy delivered by these projects contributes negatively to carbon emission reductions, and the more electricity delivered, the greater the negative impact. For example, if the delivered electricity increases from 12.047 billion kWh in 2022 to 20.337 billion kWh in 2023, the incremental carbon emissions will increase from 902,830.64 tCO2 to 1,565,615.36 tCO2.

[0044] Conversely, the Lugu DC and Ximeng-Shandong AC projects have significantly facilitated the export of surplus renewable energy power from Northeast and North China, significantly boosting local renewable energy consumption and contributing significantly to carbon emissions reductions. The proportion of renewable energy power consumed by the Lugu DC project is projected to increase significantly from 8.743 billion kWh in 2022 to 18.899 billion kWh in 2023, with corresponding carbon emissions reductions also increasing significantly from 2,917,640.69 tCO2 in 2022 to 8,923,747.37 tCO2. In comparison, the Ximeng-Shandong project consumes a larger amount of new energy electricity, but the change is smaller, only slightly increasing from 21.316 billion kWh in 2022 to 22.755 billion kWh in 2023. The corresponding carbon emission reduction changes are also relatively stable (from 10,866,030.34 tCO2 in 2022 to 11,018,003.29 tCO2 in 2023).

[0045] The carbon reduction benefits of UHV projects are positively correlated with the amount of renewable energy they absorb: the more renewable energy a transmission channel absorbs, the greater its contribution to carbon reduction; conversely, the less renewable energy a channel absorbs, the lower its contribution. This demonstrates that the capacity to absorb renewable energy is a key factor in determining the carbon reduction effectiveness of UHV projects. Therefore, UHV transmission lines, when coordinated with the planning, construction, and grid connection of renewable energy power generation bases, can effectively increase the proportion of non-fossil energy on both the generation and load sides, replacing traditional fossil energy with clean energy, thereby contributing to a reduction in overall carbon emissions from the power system.

[0046] From formula (10), we can see that the total carbon emission reduction of the UHV project is the sum of the carbon emission reduction on the power generation side, the grid side, and the load side. The detailed calculation results of the carbon emission reduction on each side of the three UHV projects are as follows: Figure 5 、 6 , as shown in 7.

Claims

1. The method for calculating carbon emission reductions in the source, grid and load during the operation phase of UHV power transmission projects is characterized by: Please follow the steps below to implement: Step 1: Determine the type of UHV power transmission project and whether it is connected to a renewable energy power plant and undertakes renewable energy transmission tasks. These projects are categorized as UHV projects that undertake renewable energy transmission tasks and those that do not. Based on the project type, define the carbon emission reduction accounting scope for the power generation side, the grid side, and the load side. Step 2: Based on the accounting scope of the power generation side, grid side and load side, determine the carbon emission reduction of the UHV power transmission project, and realize the full-process accounting of carbon emission reduction during the operation phase of the UHV project.

2. The method for calculating carbon emission reductions in the source grid during the operation phase of a UHV power transmission project according to claim 1 is characterized in that: The specific accounting scope of the power generation side of the UHV project that undertakes the task of transmitting new energy as described in step 1 is: Assuming that after the establishment of the UHV power transmission project, the proportion of fossil energy in the power transmitted by each power plant is: , ,…, , the local load power supply of each power plant is , ,…… , from which we can get the proportion of fossil energy electricity in the total electricity on the power generation side of a certain UHV power transmission project for: （1） Where n is the number of power plants; The proportion of non-fossil energy electricity in the total electricity for: （2） Assume that before the project is built, the proportion of fossil energy in the electricity delivered by each power plant is , ,…, , and the corresponding average fossil energy electricity is obtained Proportion and average non-fossil energy electricity proportion , the carbon emission reduction on the power generation side can be obtained, as shown in formula (5): （3） （4） （5） Where, is the carbon emission reduction on the power generation side, is the difference in the average proportion of fossil energy electricity before and after the construction of the UHV power transmission project. The power supply amount of the power generation side to the users in the area, is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal, where The amount of electricity supplied to the local load of each power plant, i ranges from 1 to n.

3. The method for calculating carbon emission reductions in the source grid during the operation phase of a UHV power transmission project according to claim 2 is characterized in that: The specific calculation scope of the grid side of the UHV project that undertakes the task of transmitting new energy in step 1 is: UHV transmission projects require supporting large-capacity converter stations or substations. The amount of SF6 contained in the equipment increases significantly, and its leakage leads to direct carbon emissions. For this part of the direct carbon emissions on the grid side, first of all, the leakage of SF6 gas takes into account the emissions generated during the equipment repair and decommissioning process. Therefore, the increase in direct carbon emissions on the grid side of the UHV power transmission project is the emissions generated by the additional SF6-containing equipment required to realize the power transmission and distribution of the project after the construction of the power transmission project. The calculation method is formula (6), specifically: （6） Where, and They represent the sulfur hexafluoride capacity on the nameplates of the newly added decommissioned equipment and repaired equipment containing sulfur hexafluoride in the UHV project; and Represent the actual recovery amount of sulfur hexafluoride of retired equipment and repaired equipment respectively; Secondly, assuming that the loss ratio of fossil energy power and non-fossil energy power during transmission is the same, for the increased carbon emissions in the transmission and distribution process after the construction of the UHV power transmission project, since non-fossil energy power is not included in the carbon emissions, the proportion of non-fossil energy power in the transmitted power is obtained, that is, the indirect carbon emissions caused by the loss of fossil energy power are calculated according to formula (8): （8） Where, Carbon emissions caused by power loss during the transmission and distribution of UHV power transmission projects; is the energy loss during transmission and distribution, MWh; is the annual average power supply emission factor of the regional power grid, t CO2 / MWh; The proportion of fossil energy in the electricity delivered; When calculating the increase in carbon emissions on the grid side, and Overlay value.

4. The method for calculating carbon emission reductions in the source grid during the operation phase of a UHV power transmission project according to claim 3 is characterized in that: The emissions generated by SF6-containing equipment are calculated using the average fugitive emission method. According to formula (7), the direct carbon emissions generated by sulfur hexafluoride equipment are calculated as follows: （7） Where, for Emission factors; For the Taiwan Sulfur hexafluoride capacity on the equipment nameplate, kg; for Annual gas leakage rate, including Average annual gas leakage rate Take 0.5%, Take 25184t CO2 / t.

5. The method for calculating carbon emission reductions in the source grid during the operation phase of a UHV power transmission project according to claim 4 is characterized in that: The load-side accounting scope of the UHV project that undertakes the task of transmitting new energy as described in step 1 is as follows: first, calculate the difference between the power transmission of a certain UHV power transmission project in a certain year and the proportion of non-fossil energy power generation in the load area, then obtain the power transmission of the UHV power transmission project, calculate the reduced power generation of coal-fired power generation in the load area, and finally obtain the carbon emission reduction caused by the UHV project in the area through the carbon emission factor; assuming that the loss ratio of fossil energy power and non-fossil energy power during the transmission process is the same, then the proportion of fossil energy power and non-fossil energy power in the transmission process and the power transmission to the load side are the same; as shown in formula (9): （9） Where, is the carbon emission reduction in the load area; The proportion of non-fossil energy in the total electricity delivered for the UHV power transmission project; The proportion of non-fossil energy in the total electricity consumed in the load area when the project is not connected; Transmit electricity for the UHV power transmission project; is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal.

6. The method for calculating carbon emission reductions in the source grid during the operation phase of a UHV power transmission project according to claim 5 is characterized in that: The carbon emission reductions of the UHV project undertaking the task of transmitting new energy are as follows: (10) Where, is the carbon emission reduction on the power generation side, is the increase in carbon emissions on the grid side, It is the carbon emission reduction on the load side.

7. The method for calculating carbon emission reductions in the source grid during the operation phase of a UHV power transmission project according to claim 1 is characterized in that: The specific accounting scope of the power generation side of the UHV project without the new energy transmission task in step 1 is: This type of UHV power transmission project is not connected to a new energy power plant, and the power it transmits is all fossil energy power. 1, the proportion of non-fossil energy electricity is 0, specifically: （11） （12） （13） Where, is the carbon emission reduction on the power generation side, is the difference in the average proportion of fossil energy electricity before and after the construction of the UHV power transmission project. The power supply amount of the power generation side to the users in the area, is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal, n is the number of power plants, where The amount of electricity supplied to the local load of each power plant, i ranges from 1 to n.

8. The method for calculating carbon emission reductions in the source grid during the operation phase of a UHV power transmission project according to claim 7 is characterized in that: The specific calculation scope of the grid side of the UHV project without the new energy transmission task mentioned in step 1 is: Calculate the direct carbon emissions generated by SF6 equipment and the indirect carbon emissions generated by line losses, taking into account the proportion of non-fossil energy in the transmitted electricity. is 0, =1, calculated according to formula (14), specifically: （14） Where, Carbon emissions caused by power loss during the transmission and distribution of UHV power transmission projects; is the power loss during transmission and distribution, MWh; is the annual average power supply emission factor of the regional power grid, t CO2 / MWh; Then, the increase in carbon emissions on the grid side is: （15） Where, As carbon emissions on the grid side increase, Direct carbon emissions caused by SF6 gas leakage, Carbon emissions caused by power loss during the transmission and distribution of UHV power transmission projects.

9. The method for calculating carbon emission reductions in the source grid during the operation phase of a UHV power transmission project according to claim 8 is characterized in that: The load-side accounting scope of the UHV project without new energy transmission tasks described in step 1 is specifically as follows: （16） Where, is the increase in carbon emissions for that load area; The proportion of fossil energy in the total electricity consumed in the load area when the project is not connected; Transmit electricity for the UHV power transmission project; is the standard coal consumption of the generating unit; is the carbon emission factor of standard coal.

10. The method for calculating carbon emission reductions in the source grid during the operation phase of an ultra-high voltage power transmission project according to claim 9 is characterized in that: The carbon emission reductions of the UHV projects that do not undertake new energy transmission tasks are as follows: （17） Where, For carbon emissions from power generation, is the increase in carbon emissions on the grid side, It is the carbon emission on the load side.

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