Carbon emission flow iterative calculation method of reference power transmission system

Abstract

The invention discloses a carbon emission flow iterative calculation method of a reference power transmission system, and relates to the field of carbon emission calculation. According to the technical scheme, the method comprises the following steps that a carbon emission flow model is established according to node carbon emission factors and branch carbon flow density; the node carbon emission factor represents indirect carbon emission corresponding to unit power consumption of each node; the branch carbon flow density describes the indirect carbon emission corresponding to the unit electric quantity flow passing through the specific line; establishing a carbon emission flow model for the power system composed of n nodes according to the step (1); according to the iteration matrix iteration carbon emission flow model of the Jacobian method, establishing a node carbon emission iteration model; and verifying the reliability and expandability of the carbon emission flow iterative algorithm by using a node system. The method is mainly used for applying a carbon emission flow theoretical model to actual carbon accounting, and comprehensive simulation verification is carried out on different node test systems so as to check the universality of the test systems.

Description

Technical Field

[0001] The present invention relates to the field of carbon emission calculation, and more specifically, to an iterative calculation method for carbon emission flow of a benchmark power transmission system. Background Art

[0002] In recent years, with the rapid development of industrialization and urbanization, human activities have continued to increase, leading to a continuous increase in the concentration of carbon dioxide in the atmosphere. This situation has attracted attention from global climate change, because the increase of greenhouse gases such as carbon dioxide will lead to the intensification of the greenhouse effect of the earth, exacerbating problems such as climate warming. Through monitoring and simulation analysis, carbon emissions in different regions can be well tracked. Studies have found that developed countries such as the United States, European countries and other regions with a high degree of industrialization have large carbon dioxide emissions, while some developing countries such as China and India are also growing rapidly, resulting in a continuous increase in the total amount of greenhouse gas emissions. In addition, carbon emission flow (CEF) is also affected by factors such as topography and climate, and there are differences in the flow of carbon dioxide under different seasons and climate conditions.

[0003] The most widely used CEF models include equilibrium models, input-output models, system dynamics models, and life cycle assessment models. Chan et al. proposed a dynamic, stochastic general equilibrium framework for carbon emissions. It integrates carbon emissions at different stages of the production chain and under various industrial shocks. It not only solves the impact of productivity improvement and structural changes on the environment, but also determines the optimal carbon tax policy under different shocks, solving key problems in carbon policy making. Lu et al. used a dynamic life cycle assessment framework to integrate the carbon footprint of solar photovoltaic panels with spatiotemporal changes. The supply chain of a carbon-neutral energy system was simulated to maximize environmental benefits. By introducing a variety of manufacturing scenarios, the assessment problem of indirect greenhouse gas emissions affected by future energy structure changes was solved, thereby improving the accuracy and applicability of the model. By adopting the CEF model, the reliance on high-carbon emission sources was successfully reduced and carbon emissions were minimized.

[0004] However, the scalability and effectiveness of these methods for different transmission grid systems still need to be verified and analyzed. Different types of power systems (such as transmission grids, distribution grids, microgrids, etc.) have different characteristics and constraints, and the CEF theory needs to be adjusted and modified according to specific circumstances. The existing technology has not verified the universality of the CEF theory, and it is impossible to reasonably evaluate the performance and adaptability of the CEF theory. Summary of the invention

[0005] The purpose of the present invention is to expand the CEF theoretical model based on tidal current, propose a carbon emission flow iteration method, and verify its convergence problem.

[0006] To achieve the above object, a method for iteratively calculating carbon emission flow of a benchmark transmission system is provided, comprising the following steps:

[0007] (1) A carbon emission flow model is established based on the node carbon emission factor and the branch carbon flow density; the node carbon emission factor represents the indirect carbon emission corresponding to the unit electricity consumption of each node; the branch carbon flow density describes the indirect carbon emission corresponding to the unit electricity flow through a specific line;

[0008] (2) establishing a carbon emission flow model for a power system consisting of n nodes according to step (1);

[0009] (3) Establishing a node carbon emission iteration model based on the iterative matrix iterative carbon emission flow model of the Jacobi method;

[0010] (4) Use the node system to verify the reliability and scalability of the carbon emission flow iteration algorithm.

[0011] In particular, the carbon emission flow model established in step (1) is expressed as:

[0012]

[0013] In the formula, l + , l - represents the branch set flowing into and out of node i, E N，i ,E G，i represent the carbon intensity at node i and the carbon emission intensity of the generator, respectively, B，l , P G，i , ρ l They represent the active power flow of branch 1, the generator injection power and the carbon flow density of branch 1 respectively.

[0014] In particular, the node carbon emission factor in step (1) is equal to the injected node carbon emission factor, and the branch carbon emission density is equal to the injected node carbon emission coefficient.

[0015] In particular, the node carbon emission coefficient in step (1) is expressed as:

[0016]

[0017] Where P j→i represents the active power injected from node j to node i, e j represents the carbon emission coefficient injected into node j. The linear equation of the node carbon emission coefficient can be expressed as:

[0018]

[0019] In particular, in step (2), for a power system consisting of n nodes, the carbon emission coefficient of each node is expressed as:

[0020]

[0021] The matrix form of the linear equation system (4) can be expressed as:

[0022]

[0023] Where P N Represents the node active power flow matrix, P B represents the branch power flow distribution matrix, E N represents the node carbon emission factor vector, P G represents the power distribution matrix injected by the generator set, E G is the carbon emission factor vector of the generator set.

[0024] In particular, the iterative matrix according to the Jacobi method in step (3) is expressed as:

[0025]

[0026] In particular, the node carbon emission iteration model in step (3) is measured by two indicators: the node carbon emission coefficient iteration equation and the node carbon emission iteration factor.

[0027] In particular, the iterative equation of the node carbon emission coefficient in step (3) is expressed as:

[0028]

[0029] In the formula, Represents the node carbon emission factor vector after k iterations.

[0030] In particular, the node carbon emission iteration factor in step (3) is expressed as:

[0031]

[0032] In the formula, Represents the carbon emission coefficient of node n calculated from k+1 iterations.

[0033] Particularly, the node system in step (4) includes an IEEE-6 node system, an IEEE-14 node system and an IEEE-39 node system.

[0034] The beneficial effects of the present invention are as follows: the present invention expands the theoretical model of carbon emission flow based on power flow. Based on the concepts of node active flux, node carbon potential, load carbon flow, etc., a carbon emission flow iteration method is proposed, and its convergence is verified. In order to apply the theoretical model of carbon emission flow to actual carbon accounting, the present invention conducts a comprehensive simulation verification of different node test systems to test its versatility. Systems of various types and capacities are selected from the IEEE benchmark node system to verify the proposed method, which proves that the method has strong adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below.

[0036] Figure 1 It is a schematic diagram of the power flow and carbon flow of each branch of the IEEE-6 bus power system of the present invention;

[0037] Figure 2 The radar diagram of active power flux at a node of the node system verification node of the embodiment of the present invention; in the figure: (a) IEEE-6 bus system (b) IEEE-14 bus system (c) IEEE-39 bus system;

[0038] Figure 3 The node system of the embodiment of the present invention verifies the node carbon intensity and load carbon emission rate at the node; in the figure: (a) IEEE-6 bus system (b) IEEE-14 bus system (c) IEEE-39 bus system. DETAILED DESCRIPTION

[0039] The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] The CEF method is a technique used to analyze the distribution of carbon emissions in power systems. In power systems, there is a close relationship between the flow of electricity and carbon emissions. Therefore, understanding the distribution of current helps to understand the distribution of carbon emissions. The CEF method takes into account multiple factors such as network topology, power line and transformer impedance, generator output, node load, etc. to more accurately assess the distribution of carbon emissions.

[0043] The present invention provides an iterative calculation method for carbon emission flow of a benchmark power transmission system, comprising the following steps:

[0044] (1) A carbon emission flow model is established based on the node carbon emission factor and branch carbon flow density. The node carbon emission factor represents the indirect carbon emissions corresponding to the unit electricity consumption of each node. The branch carbon flow density describes the indirect carbon emissions corresponding to the unit electricity flow through a specific line. By tracking these two indicators, we can better understand the carbon emission status of the power system and take corresponding measures to reduce carbon emissions.

[0045] The carbon emission flow model established in step (1) is expressed as:

[0046]

[0047] In the formula, l + , l - represents the branch set flowing into and out of node i, E N，i ,E G，i represent the carbon intensity at node i and the carbon emission intensity of the generator, respectively, B，l , P G，i , ρ l They represent the active power flow of branch 1, the generator injection power and the carbon flow density of branch 1 respectively.

[0048] like Figure 1 As shown, all injection branches b of node i 1，...，n The carbon flow density is equal to its injection into node j 1，...，nTherefore, the carbon emission factor of node i can be injected into nodes j1, j2, ...j n That is, the node carbon emission factor is equal to the injected node carbon emission factor, and the branch carbon emission density is equal to the injected node carbon emission coefficient.

[0049] The node carbon emission coefficient in step (1) is expressed as:

[0050]

[0051] Where P j→i represents the active power injected from node j to node i, e j represents the carbon emission coefficient injected into node j. The linear equation of the node carbon emission coefficient can be expressed as:

[0052]

[0053] (2) establishing a carbon emission flow model for a power system consisting of n nodes according to step (1);

[0054] In step (2), for a power system consisting of n nodes, the carbon emission coefficient of each node is expressed as:

[0055]

[0056] The matrix form of the linear equation system (4) can be expressed as:

[0057]

[0058] Among them, P N represents the node active power flow matrix, which is an N-order diagonal matrix. The diagonal element P in the ith row Nii P represents the total active power injected into node i by branches and generators. B represents the branch power flow distribution matrix, which is an N-order square matrix. The non-diagonal element P Bij It represents the active power injected from node j to node i. N represents the node carbon emission factor vector, and P G represents the power distribution matrix injected by the generator set, E G is the carbon emission factor vector of the generator set.

[0059] In equation (5), the coefficient matrix of the linear system is expressed as To solve the iteration matrix, the coefficient matrix is ​​decomposed into the sum of three parts, where D is a diagonal matrix, L is a strict lower triangular matrix, and U is a strict upper triangular matrix. N is a diagonal matrix, equal to D, Equal to -(L+U).

[0060] (3) The node carbon emission iteration model is established based on the iterative matrix iterative carbon emission flow model of the Jacobi method. The node carbon emission iteration model is measured by two indicators: the node carbon emission coefficient iteration equation and the node carbon emission iteration factor.

[0061] The iteration matrix of the Jacobi method in step (3) is:

[0062]

[0063] There is no traffic on the lines between the suspended nodes and other nodes in the power grid, so it will not affect the calculation of CEF in the power system. If all suspended nodes are excluded when calculating CEF, the power grid becomes a connected network, then P N The diagonal elements of do not contain non-zero elements. Therefore, P N The reversibility is guaranteed.

[0064] The iterative equation of the node carbon emission coefficient is expressed as:

[0065]

[0066] In the formula, represents the node carbon emission factor vector after k iterations. From the perspective of the entire power system, with flow distribution, generator injection distribution and carbon emission factor as boundary conditions, iterative calculation is performed from any initial vector The node carbon emission factor vector generated after each iteration is used as the initial value of the next iteration, and k+1 linear iterations are performed until the result converges to In essence, each iteration process is gradually approaching the converged node carbon emission factor.

[0067] The node carbon emission iteration factor is expressed as:

[0068]

[0069] In the formula, Represents the carbon emission coefficient of node n calculated from k+1 iterations.

[0070] (4) Use the node system to verify the reliability and scalability of the carbon emission flow iteration algorithm.

[0071] In order to verify the reliability and scalability of the carbon emission flow algorithm based on power flow proposed in the present invention, the carbon emission flow iteration algorithm was verified using IEEE-6, IEEE-14 and IEEE-39 node systems. The scale of the IEEE-6 node system is relatively small, which is suitable for preliminary verification of the effectiveness and accuracy of the carbon emission flow calculation method based on power flow. As a medium-sized power system test platform, the IEEE-14 node system has a moderate installed capacity, generally ranging from hundreds of megawatts to thousands of megawatts. As for the IEEE-39 node system, it is used to test larger and more complex power systems. Due to the relatively large load scale, it usually contains more load nodes and more power equipment, reflecting a more realistic power system scenario. Figure 2 The active power flows at the nodes of three test systems are described.

[0072] exist Figure 2 In (a), the maximum active power flow occurs at node 2, indicating that the generator sets contribute greatly to the carbon potential of nodes 2 and 1. Figure 2 In (b), the highest active power flow occurs at node 1. The active power flow represents the "absolute amount" of active power flowing into the node in the flow direction. Generator unit 1 outputs the active power flowing into node 1, resulting in a significant increase in the power of node 1. Figure 2 In (c), the active power flow at node 39 is the highest because a generator with a maximum output power of 1000 MW is installed, resulting in the maximum active power flowing into node 39.

[0073] Figure 3 The carbon intensity and load carbon flow of each node in the three test systems are shown. It is obvious that the carbon intensity of the node is significantly higher than the load carbon flow. Node carbon intensity refers to the carbon emission potential or capacity of each node in the CEF model. It reflects the degree of influence of the node on carbon emissions and is usually related to the power load and carbon emission coefficient of the node. The size of the node carbon intensity will affect the distribution and flow of carbon emissions in the power system. On the other hand, the load carbon flow refers to the carbon flux related to the power load of each node in the CEF model. It represents the carbon emissions corresponding to a unit power load and can be used to evaluate the contribution of different loads to the carbon emissions of the power system.

[0074] 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 can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention 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 of the claims.

Claims

1. A method for iteratively calculating carbon emission flow of a benchmark power transmission system, characterized by: The following steps are involved: (1) Establish a carbon emission flow model based on the node carbon emission factor and branch carbon flow density; The node carbon emission factor represents the indirect carbon emission corresponding to the unit electricity consumption of each node; the branch carbon flow density describes the indirect carbon emission corresponding to the unit electricity flow through a specific line; (2) establishing a carbon emission flow model for a power system consisting of n nodes according to step (1); (3) Establishing a node carbon emission iteration model based on the iterative matrix iterative carbon emission flow model of the Jacobi method; (4) Use the node system to verify the reliability and scalability of the carbon emission flow iteration algorithm.

2. The iterative calculation method for carbon emission flow of a benchmark power transmission system according to claim 1, characterized in that: The carbon emission flow model established in step (1) is expressed as: In the formula, l + , l - represents the branch set flowing into and out of node i, E N，i ,E G，i represent the carbon intensity at node i and the carbon emission intensity of the generator, respectively, B，l , P G，i , ρ l They represent the active power flow of branch 1, the generator injection power and the carbon flow density of branch 1 respectively.

3. The iterative calculation method of carbon emission flow of a benchmark power transmission system according to claim 1, characterized in that: The node carbon emission factor in step (1) is equal to the injected node carbon emission factor, and the branch carbon emission density is equal to the injected node carbon emission coefficient.

4. The iterative calculation method for carbon emission flow of a benchmark power transmission system according to claim 1, characterized in that: The node carbon emission coefficient in step (1) is expressed as: Where P j→i represents the active power injected from node j to node i, e j represents the carbon emission coefficient injected into node j. The linear equation of the node carbon emission coefficient can be expressed as:

5. The iterative calculation method of carbon emission flow of a benchmark power transmission system according to claim 1, characterized in that: In step (2), for a power system consisting of n nodes, the carbon emission coefficient of each node is expressed as: The matrix form of the linear equation system (4) can be expressed as: Where P N Represents the node active power flow matrix, P B represents the branch power flow distribution matrix, E N represents the node carbon emission factor vector, P G represents the power distribution matrix injected by the generator set, E G is the carbon emission factor vector of the generator set.

6. The iterative calculation method for carbon emission flow of a benchmark power transmission system according to claim 1, characterized in that: The iterative matrix according to the Jacobi method in step (3) is expressed as: B=-D -1 (L+U)=P N -1 P B T (6)。 7. The iterative calculation method for carbon emission flow of a benchmark power transmission system according to claim 1, characterized in that: The node carbon emission iteration model in step (3) is measured by two indicators: the node carbon emission coefficient iteration equation and the node carbon emission iteration factor.

8. The iterative calculation method for carbon emission flow of a benchmark power transmission system according to claim 1, characterized in that: The iterative equation of the node carbon emission coefficient in step (3) is expressed as: E N (k+1) =P N -1 ·P B T ·E N (k)+R N -1 ·P G T ·E G (7); In the formula, Represents the node carbon emission factor vector after k iterations.

9. The iterative calculation method for carbon emission flow of a benchmark power transmission system according to claim 1, characterized in that: The node carbon emission iteration factor in step (3) is expressed as: In the formula, Represents the carbon emission coefficient of node n calculated from k+1 iterations.

10. The iterative calculation method of carbon emission flow of a benchmark power transmission system according to claim 1, characterized in that: The node system in step (4) includes an IEEE-6 node system, an IEEE-14 node system and an IEEE-39 node system.

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