A method and device for multi-stage expansion planning of distribution network considering carbon emission reduction

Abstract

The present invention provides a method and device for planning a multi-stage expansion of a distribution network taking carbon emission reduction into account, and relates to the technical field of distribution network planning. First, referring to the node load and the capacity of the substation in the initial stage, a carbon quota quantification model is constructed by applying an exponential function to effectively reflect the volatility characteristics in the process of carbon emission reduction; then, a method combining incremental ring detection and depth-first search is used to deal with the constraints of the radial topology of the distribution network, and the idea of ​​disconnection and ring unwinding is used to ensure that the planning process can adapt to the actual needs of multi-stage expansion; then, a multi-stage expansion planning model is constructed and solved with the minimization of the sum of the construction cost, operation cost and carbon cost of the distribution network within the planning cycle as the objective function. And the method is verified based on a planning example of a 24-node distribution network. The present invention can construct a multi-stage expansion planning model containing carbon emission costs, and provide a reference solution for achieving efficient and reliable distribution network operation.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network planning, and in particular to a distribution network multi-stage expansion planning method and device taking carbon emission reduction into account. Background Art

[0002] Against the backdrop of global climate change and increasingly severe energy challenges, promoting the consumption of new energy and reducing carbon emissions have become a strategic direction pursued by the world. The planning and research of low-carbon distribution networks can effectively improve the access capacity of new energy, thereby promoting the development of green energy, improving energy utilization and promoting the consumption of new energy.

[0003] For a long time, scholars at home and abroad have conducted in-depth research on the expansion planning of distribution networks. Existing research mainly focuses on a single planning stage, but factors such as future load growth and changes in distributed power access have not been fully considered, and there is a lack of consideration of the interaction between multi-stage investment and operation. Some studies have also comprehensively considered the distribution network expansion planning and the site selection and sizing of equipment such as distributed power sources by constructing a multi-stage coordinated planning model, but carbon emissions factors have not been considered in the planning problem. In addition, although a variety of methods have been proposed for the radial topology constraint problem in distribution network planning, such as the spanning tree method and virtual power flow, there are still limitations and long solution time problems, especially in the application of multi-stage planning, which needs further research. Summary of the invention

[0004] The purpose of the present invention is to provide a method and device for multi-stage expansion planning of a distribution network taking into account carbon emission reduction, which is used to solve the problems existing in the expansion planning of the distribution network in the prior art, such as the lack of full consideration of relevant factors, limitations and long solution time. It can construct a multi-stage expansion planning model containing carbon emission costs, provide a reference solution for achieving efficient and reliable distribution network operation, and meet the actual needs of carbon emission reduction.

[0005] In order to achieve the above object, the present invention provides a distribution network multi-stage expansion planning method taking into account carbon emission reduction, comprising:

[0006] Step 1: Construct a carbon quota quantification model based on the node load and substation capacity in the initial stage;

[0007] Step 2: Determine the constraints applicable to the multi-stage expansion plan;

[0008] Step 3: Based on the carbon quota quantification model and the constraints applicable to the multi-stage expansion planning, a multi-stage expansion planning model with carbon emission costs is constructed;

[0009] Step 4: Use the second-order cone constraints to solve the multi-stage extended planning model.

[0010] According to a multi-stage expansion planning method for a distribution network taking carbon emission reduction into account provided by the present invention, the carbon quota quantification model is:

[0011]

[0012]

[0013] In the formula, For the x Annual carbon quota; The initial carbon quota for the distribution network; is the carbon reduction pressure factor of the distribution network; is the total active power load of the distribution network in the first stage; is the total active power capacity of existing substations in the distribution network; It is the carbon emission per unit active power output.

[0014] According to a multi-stage expansion planning method for a distribution network taking carbon emission reduction into account provided by the present invention, the carbon quota quantification model is:

[0015]

[0016]

[0017] In the formula, For the x Annual carbon quota; The initial carbon quota for the distribution network; is the amplitude of the disturbance term; Fluctuation cycles for short-term impacts; is the carbon reduction pressure factor of the distribution network; is the total active power load of the distribution network in the first stage; is the total active power capacity of existing substations in the distribution network; It is the carbon emission per unit active power output.

[0018] According to a method for multi-stage expansion planning of a distribution network taking carbon emission reduction into consideration provided by the present invention, step 2 specifically includes: for the constraints of the radial topology of the distribution network, a method combining incremental ring detection and depth-first search is adopted, and a strategy of disconnection and ring unwinding is adopted to determine the constraints applicable to the multi-stage expansion planning as follows:

[0019]

[0020] In the formula, is 0 or 1, when t Nodes in the distribution network i and j The line between them has been built. is 1, when the node i and j The line between them has not been built. is 0; 、 Respectively represent t The set of all rings in the distribution network at each stage and the set of paths between all root nodes; Representation Node i and j The lines between For the t Any ring in the distribution network of each stage, is the number of nodes in any ring; For the t Any path between all root nodes in the distribution network of the stage, is the number of nodes in any path; E Represents the set of all lines in the distribution network; For the t The number of all nodes in the distribution network at each stage; For the t The number of all root nodes in the distribution network at each stage.

[0021] According to a distribution network multi-stage expansion planning method taking carbon emission reduction into account provided by the present invention, step 3 specifically includes:

[0022] Determine the construction cost, operating cost, and carbon cost of the multi-stage expansion planning model;

[0023] The objective function of the multi-stage expansion planning model is constructed based on the construction cost, operation cost, carbon cost and carbon quota quantitative model;

[0024] Based on the constraints applicable to multi-stage expansion planning, determine the constraints of the multi-stage expansion planning model.

[0025] According to a multi-stage expansion planning method for a distribution network taking carbon emission reduction into account provided by the present invention, the construction cost is:

[0026]

[0027] in, For construction costs; The number of stages for planning; is the total number of years in each stage; , , They represent the collection of lines, substations, and distributed generation respectively; , , Respectively t The investment cost of the lines, substations and distributed power sources in each stage; t Nodes in the distribution network i and j The line between them has been built. is 1, when the node i and j The line between them has not been built. is 0; when t Nodes in the distribution network i Substations have been built. is 1, when the node i The substations in the area have not been built. is 0; when t Nodes in the distribution network i Distributed power sources have been built. is 1, when the node i Distributed power generation has not been built. is 0; , , Respectively represent t The construction costs of the lines, substations and distributed generation in each stage; , , are the depreciation coefficients of lines, substations and distributed generation respectively; r is the discount rate;

[0028] The running cost is:

[0029]

[0030] in, For operating costs; For the t The operating cost of the substation in each stage, is the operating cost of the substation per square unit of energy, Active power generated by the substation; For the t The operating cost of distributed power generation in each stage, is the operating cost of distributed power generation per unit energy squared, The active power generated by distributed power sources; For the t Line network loss costs in each stage, is the unit network loss cost of the line, For Node i and j The resistance of the line between For Node i andj The square of the current in the line between

[0031] The carbon cost is:

[0032]

[0033] in, for carbon costs; For the t Carbon emission cost at each stage; is the carbon trading price, For the t Active power generated by the substation in each stage; is the total number of hours for each phase; For the t The active power generated by the distributed power generation in each stage; Carbon emissions from power generation for distributed power units; For the t The carbon quota of the distribution network in each stage.

[0034] According to a multi-stage expansion planning method for a distribution network taking carbon emission reduction into account provided by the present invention, the first t The expression of carbon quota of the distribution network in each stage is:

[0035]

[0036] According to a multi-stage expansion planning method for a distribution network taking carbon emission reduction into consideration provided by the present invention, the constraints of the multi-stage expansion planning model include new construction constraints, power flow constraints and radial topology constraints; the new construction constraints are:

[0037]

[0038] Among them, when the nodes in the distribution network are in the initial state i and j The line between them has been built. is 1, when the node i and j The line between them has not been built. is 0; when the node in the initial state distribution network i Substations have been built. is 1, when the node i The substations in the area have not been built. is 0;

[0039] The power flow constraint is:

[0040]

[0041]

[0042] in, For the t Phase Node i Active load; For the t Phase Node i Reactive load; , Respectively t Nodes in the distribution network i, j The square of the voltage amplitude; , Respectively t The flow through the node in the distribution network in the stage i and j Active power and reactive power of the lines between them; , Respectively t The flow through the node in the distribution network in the stage i and k Active power and reactive power of the lines between them; , Node i and j The resistance and reactance of the lines between them; , Node i and k The resistance and reactance of the lines between them; For the t Phases flow through nodes i and j The square of the current amplitude on the line between them; For the t Phases flow through nodes i and k The square of the current amplitude on the line between them; is the set of all nodes; is a maximum positive real number;

[0043] The radial topology constraints include:

[0044]

[0045]

[0046]

[0047] Among them, two substations and exist at the same time; For the t Phase Substation and The set of paths between .

[0048] According to a multi-stage expansion planning method for a distribution network taking carbon emission reduction into consideration provided by the present invention, the constraints of the multi-stage expansion planning model also include line power constraints, line capacity limit constraints, and substation output constraints, and the expression is:

[0049]

[0050] In the formula, , are the upper and lower limits of the node voltage respectively; Representation Node i and j The square of the maximum current allowed to flow in the line between them; Indicates substation i Rated capacity; For distributed power i Rated capacity.

[0051] In a second aspect, the present invention provides a distribution network multi-stage expansion planning device taking into account carbon emission reduction, comprising:

[0052] The first construction unit is used to construct a carbon quota quantification model according to the node load and substation capacity in the initial stage;

[0053] a determination unit for determining constraints applicable to multi-stage expansion planning;

[0054] The second construction unit is used to construct a multi-stage expansion planning model containing carbon emission costs based on the carbon quota quantification model and the constraint conditions applicable to the multi-stage expansion planning;

[0055] A solving unit for solving multi-stage extended programming models using second-order cone constraints.

[0056] The present invention provides a method and device for planning a multi-stage expansion of a distribution network taking carbon emission reduction into account. First, referring to the node load and the capacity of the substation in the initial stage, a carbon quota quantification model is constructed by applying an exponential function to effectively reflect the volatility characteristics in the process of carbon emission reduction; then, a method combining incremental ring detection and depth-first search is used to deal with the constraints of the radial topology of the distribution network, and the idea of ​​disconnection and ring unwinding is used to ensure that the planning process can adapt to the actual needs of multi-stage expansion; then, a multi-stage expansion planning model is constructed and solved with the objective function of minimizing the sum of the construction cost, operation cost and carbon cost of the distribution network within the planning period. And the method is verified based on a planning example of a 24-node distribution network. The present invention can construct a multi-stage expansion planning model containing carbon emission costs, providing a reference solution for achieving efficient and reliable distribution network operation.

[0057] Compared with the prior art, the present invention has the following advantages:

[0058] 1. Constructing a carbon quota quantitative model and dynamically evaluating the carbon emission reduction pressure at each stage can provide a certain theoretical basis for the planning and decision-making of the distribution network.

[0059] 2. The proposed radial constraint processing method can gradually identify rings and paths and enhance the effectiveness of radial topology constraints, reducing the complexity of model solution. By gradually enhancing constraints, the flexibility and adaptability of planning are effectively improved, which can better cope with the dynamic changes and complexity of the distribution network and is applicable to other application scenarios that need to consider radial topology.

[0060] 3. The introduction of carbon emission reduction factors promoted the early construction of distributed power sources in the distribution network, which not only met the load demand, but also reduced the active output of the substation, thereby effectively reducing the overall carbon emissions. Overall, although the pressure of carbon emission reduction increases the construction cost in the short term, in the long run, it not only helps to achieve environmental protection goals, but also improves the economic benefits of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0062] In the attached picture:

[0063] Figure 1 It is a graph showing the change of carbon quota under different parameters of the present invention;

[0064] Figure 2 This is a schematic diagram of a 24-node power distribution network of the present invention;

[0065] Figure 3 This is a schematic diagram of the distribution network expansion planning results under different schemes;

[0066] Figure 4 This is a flow chart of the multi-stage expansion planning method of the distribution network taking carbon emission reduction into consideration according to the present invention. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments 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.

[0068] Some embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. The following embodiments and features in the embodiments may be combined with each other without conflict. If there is no necessary order for the steps described in the embodiments, the order is only an example and should not be regarded as a limitation. A person of ordinary skill in the art may adjust the order of the steps without destroying the logic.

[0069] See also Figure 4 The embodiment of the present invention provides a method for multi-stage expansion planning of a distribution network taking carbon emission reduction into account, comprising:

[0070] Step 1: Construct a carbon quota quantification model based on the node load and substation capacity in the initial stage;

[0071] Specifically, the reduction of carbon quotas is a dynamic process in which multiple factors work together. Over time, policy strengthening and technological progress have accelerated the pace of emission reduction, and the exponential function can simulate this trend well: emission reduction progress is slow at first, but then gradually accelerates.

[0072] Furthermore, carbon quotas The specific formula is as follows:

[0073]

[0074] in, For the x Annual carbon quota; The initial carbon quota for the distribution network; is the carbon emission reduction pressure factor of the distribution network, and its value range is The initial carbon quota is determined based on the total load in the first phase and the capacity of the existing substations in the distribution network. The specific formula is as follows:

[0075]

[0076] Among them, 8760 is the total number of hours in a year; is the total active power load of the distribution network in the first stage; is the total active power capacity of existing substations in the distribution network; It is the carbon emission per unit active power output.

[0077] In some embodiments, in order to make the carbon quota curve not only show an overall downward trend, but also reflect the local fluctuations that may occur in the actual emission reduction process, a disturbance term is added to the aforementioned carbon quota to simulate the short-term impact caused by policy, technology or economic changes. The specific formula is as follows:

[0078]

[0079] in, is the disturbance term amplitude, and its value range is ; It is a fluctuation cycle with short-term impact.

[0080] From the formula, we can see that by adjusting and The value of can control the intensity and frequency of short-term fluctuations, so that the carbon quota curve will show local fluctuations in the process of overall decline; by adjusting The frequency of carbon quota reduction can be controlled, such as Figure 1 shown.

[0081] from Figure 1 The results in the paper show that the constructed carbon quota model not only retains the long-term trend of gradually reducing carbon emissions, but also introduces certain short-term uncertainties. This design makes the carbon quota model more in line with the actual situation and can effectively reflect the volatility characteristics of the carbon emission reduction process.

[0082] Step 2: Determine the constraints applicable to the multi-stage expansion plan;

[0083] Aiming at the constraints of the radial topology of the distribution network, a method combining incremental ring detection and depth-first search is adopted, and a strategy of disconnection and ring breaking is adopted to ensure that the planning process can adapt to the actual needs of multi-stage expansion and determine the constraints suitable for multi-stage expansion planning.

[0084] Furthermore, the specific formula based on the radial topology constraint of disconnection and ring breaking is as follows:

[0085]

[0086] in, It is a 0-1 variable, representing a node i and j Whether the line between them is built, 0 means it is not built; C.P They represent the set of all rings in the distribution network and the set of paths between all root nodes respectively; Representation Node i and j The lines between Represents any ring in the network; Represents any path between root nodes; E , N , R Respectively represent the set of all lines, the set of all nodes, and the set of all root nodes; Represents the number of elements in the collection.

[0087] Furthermore, for the multi-stage optimization planning problem of distribution network, this paper proposes an innovative loop and path search method, which is centered on key node priority search and incremental detection, aiming to efficiently identify all loops and paths in the distribution network. By recording the search results in stages, these data can be used as constraints in the subsequent extended planning stage to support more accurate planning decisions.

[0088] For a given distribution network topology, it can be simplified into an undirected graph ,in is a collection of substations and load nodes. is a set of paths between different nodes. In the distribution network, the number of adjacent nodes of some nodes is zero or very small, which makes it extremely unlikely that these nodes will form a ring. Therefore, the degree centrality of different nodes can be calculated and arranged in descending order to form a search priority index. The degree centrality is calculated as follows: The specific formula is as follows:

[0089]

[0090] in, Representatives and Nodes The number of adjacent nodes; is the total number of nodes in the network.

[0091] Furthermore, the core concept of the incremental loop detection method is to perform loop detection only on newly added nodes or edges and their directly connected local networks based on the existing network structure, avoiding repeated traversal of the entire network. This method improves detection efficiency and reduces the consumption of computing resources. The basic principle of the depth-first search algorithm is to start from a node, explore in depth in one direction until it is impossible to continue, and then backtrack to the previous node and try other possible paths. If a node that has been visited is returned during the exploration process, it means that a loop has been detected. This algorithm can effectively explore all possible paths in the network and identify loops.

[0092] According to the determined priority index, combined with the incremental ring detection idea, the depth-first search algorithm can be used to realize the dynamic identification of paths and rings in the distribution network. The steps are as follows:

[0093] An undirected graph of input distribution network with substation nodes (root nodes) and load nodes in different stages;

[0094] Calculate the degree centrality of the newly added nodes in each stage Used to determine the nodes that need to be processed first. Nodes with higher values ​​are searched and updated first;

[0095] Perform a depth-first search on the local area connected to the newly added load node to identify the loops and paths that appear in this stage and avoid global search;

[0096] Output all paths between all rings and root nodes in the network at each planning stage.

[0097] On this basis, the above formula is improved to form constraints suitable for multi-stage planning. The specific formula is as follows:

[0098]

[0099] The variables are superscripted t Representing the planning t stage.

[0100] Step 3: Based on the carbon quota quantification model and the constraints applicable to the multi-stage expansion planning, a multi-stage expansion planning model with carbon emission costs is constructed;

[0101] Step 4: Use the second-order cone constraints to solve the multi-stage extended planning model.

[0102] Specifically, step 3 includes:

[0103] Determine the construction cost, operating cost, and carbon cost of the multi-stage expansion planning model;

[0104] The objective function of the multi-stage expansion planning model is constructed based on the construction cost, operation cost, carbon cost and carbon quota quantitative model;

[0105] Based on the constraints applicable to multi-stage expansion planning, determine the constraints of the multi-stage expansion planning model.

[0106] Among them, the construction cost is:

[0107] The construction cost of the distribution network consists of three parts: lines, substations and distributed power sources. The full life cycle investment of the three is spread over each year and then discounted and summed up. The specific formula is as follows:

[0108]

[0109] in, The number of stages for planning; is the total number of years in each stage; and Respectively represent Stage and Year; , , They represent the collection of lines, substations, and distributed power sources respectively; , , They are the stage investment costs of lines, substations, and distributed generation; , , They are all 0-1 variables, representing whether the line, substation, and distributed generation have been built, and 0 means no construction; , , They represent the construction costs of lines, substations, and distributed generation respectively; , , are the depreciation coefficients of lines, substations and distributed generation respectively; r is the discount rate.

[0110] Running costs:

[0111] The operating cost consists of three parts: substation operating cost, distributed power supply operating cost and network loss cost. The specific formula is as follows:

[0112]

[0113] in, is the substation operation cost, is the operating cost of the substation per square unit of energy, Active power generated by the substation; is the operating cost of the distributed power generation stage, is the operating cost of distributed power generation per unit energy squared, The active power generated by distributed power sources; is the line network loss cost, is the unit network loss cost of the line, For line The resistance, line The square of the current.

[0114] Carbon costs:

[0115] The carbon cost of the distribution network is mainly determined by the difference between the carbon emission price and the actual carbon emissions and carbon quota. The specific formula is as follows:

[0116]

[0117] in, For thet Carbon emission cost at each stage; is the carbon trading price, For the t Active power generated by the substation in each stage; is the total number of hours for each stage, ; For the t The active power generated by the distributed power generation in each stage; Carbon emissions from power generation for distributed power units; For the t The carbon quota of the distribution network in each stage.

[0118] Finally available Specific expression:

[0119]

[0120] Furthermore, the above three costs are converted into current present values ​​through the discount rate, taking into account the impact of time on costs, which facilitates unified comparison and decision-making.

[0121] The constraints of the multi-stage expansion planning model include new construction constraints, power flow constraints, and radial topology constraints. Among them, new construction constraints:

[0122]

[0123] in, and They represent the initial states of the line and substation respectively. When the nodes in the distribution network are in the initial state i and j The line between them has been built. is 1, when the node i and j The line between them has not been built. is 0; when the node in the initial state distribution network i Substations have been built. is 1, when the node i The substations in the area have not been built. The above constraint indicates that duplication of lines and substations is not allowed within the planning period.

[0124] Power flow constraints:

[0125] The traditional power flow equation is nonlinear. Redefining the power flow equation using phase angle relaxation and second-order cone relaxation can solve this problem and is conducive to solving the planning model. The following are the power flow constraints in different stages.

[0126] The node power balance constraints are as follows:

[0127]

[0128] For Node and nodes The voltage relationship between them is defined as follows:

[0129]

[0130] The specific formula of the second-order cone form of the power constraint is as follows:

[0131]

[0132] In the above power flow constraint formula, For the t Phase Node i Active load; For the t Phase Node i Reactive load; , Respectively t Nodes in the distribution network i, j The square of the voltage amplitude; , Respectively t The flow through the node in the distribution network in the stage i and j Active power and reactive power of the lines between them; , Respectively t The flow through the node in the distribution network in the stage i and k Active power and reactive power of the lines between them; , Node i and j The resistance and reactance of the lines between them; , Node i and k The resistance and reactance of the lines between them; For the t Phases flow through nodes i and j The square of the current amplitude on the line between them; For the t Phases flow through nodes i and k The square of the current amplitude on the line between them; is the set of all nodes; is a maximum positive real number.

[0133] Radial topology constraints:

[0134]

[0135] The formula indicates that when two substations and When they exist at the same time, the path between them must be disconnected. On the other hand, considering the extremely large number, and When they do not exist at the same time, the constraint no longer applies.

[0136]

[0137] This formula indicates that at any stage, at least one line in the ring of the distribution network is in a disconnected state.

[0138]

[0139] This formula indicates that the number of lines in the distribution network at any stage is equal to the number of nodes at that time minus the number of substations.

[0140] In the above radial topology constraint formula, For stage Substation and The set of paths between is a very large positive real number; the definitions of other variables remain the same as before.

[0141] Other constraints:

[0142] In addition to the above constraints, it is also necessary to consider line power constraints, line capacity constraints, substation output constraints and other constraints. The specific formula is as follows:

[0143]

[0144] in, , Respectively represent the upper and lower limits of the node voltage; Representative line The square of the maximum current allowed to flow; Represents the rated capacity of the substation; is the rated capacity of the distributed power source.

[0145] Combining the above steps, taking the IEEE-24 node system as an example, the effectiveness and superiority of this method are verified. Figure 2 The 24-node distribution network expansion planning example shown in the figure considers three expansion planning stages, with a number of years in each stage. The period is 5 years, the discount rate is 7.1%, and the carbon reduction pressure factor of the distribution network is Set to 0.4, the disturbance term amplitude is 0.05, the fluctuation cycle of short-term impact For 2 years.

[0146] In order to verify the effectiveness of the multi-stage expansion planning method provided by the present invention, three different planning schemes are set up for comparison:

[0147] Option 1: Multi-stage expansion planning of active distribution network without distributed generation;

[0148] Option 2: Multi-stage expansion planning of active distribution network including distributed generation;

[0149] Option 3: Multi-stage expansion planning of active distribution networks including distributed generation sources taking into account carbon emission reduction pressure.

[0150] In order to verify the rationality of the method proposed in the present invention, the present invention adopts a radial topology processing method to identify the rings and paths in the 24-node example, and the results are shown in Table 1. As can be seen from Table 1, with the gradual access of load nodes, the number of rings and paths in the distribution network gradually increases. In the first stage, the radial constraint failed to take effect because the path P between the loop C and the root node (substation) could not be detected; in the second stage, the constraint formula related to the path P also failed to take effect. It was not until the third stage that the complete radial topology constraint was formed.

[0151] Table 1. Ring and path identification results of 24 nodes in different stages

[0152]

[0153] By gradually identifying rings and paths according to the load access situation, the effectiveness of radial topology constraints is enhanced, thereby reducing unnecessary global searches, focusing on key nodes and constraints, and effectively reducing computational complexity. In addition, incremental detection and local update strategies can quickly adjust the model to cope with changes in newly added load nodes. This method not only improves the solution efficiency, but also enhances the flexibility and practicality of distribution network expansion planning. By gradually strengthening constraints, the method proposed in the present invention effectively improves the flexibility and adaptability of planning, enabling it to better cope with the dynamic changes and complexity of the distribution network.

[0154] The relevant results obtained after solving the distribution network expansion planning model under three different schemes are shown in the figure below: Figure 3 shown. Figure 3 It intuitively shows the changes in network topology and the access of distributed generation in each planning stage as the load is added. Table 2, Table 3, and Table 4 respectively present the detailed costs of distribution network expansion planning under the three schemes.

[0155] Table 2. Detailed cost of distribution network expansion planning for Scheme 1

[0156]

[0157] Table 3. Detailed cost of distribution network expansion planning for Option 2

[0158]

[0159] Table 4. Detailed cost of distribution network expansion planning for Scheme 3

[0160]

[0161] right Figure 3 From the results analysis of Table 2, Table 3, and Table 4, it can be seen that the access of distributed power sources not only delays the construction demand of substations, but also significantly reduces the operating cost of distribution networks in the long term, reflecting better economic efficiency. At the same time, the introduction of carbon emission reduction pressure has prompted the distribution network to deploy more distributed power sources in advance, thereby effectively reducing the active power output and overall carbon emissions of substations. Under the dual effects of carbon quota profits and distributed power advantages, although the construction cost has increased, Scheme 3 shows lower total cost and higher economic benefits compared with other schemes, especially in achieving a balance between economic and environmental goals in long-term operation.

[0162] In summary, the method and device for multi-stage expansion planning of distribution networks taking carbon emission reduction into account provided by the present invention propose a quantitative model based on carbon quotas, which is used to dynamically evaluate the carbon emission reduction pressure at each stage, and provide a theoretical basis for the planning and decision-making of distribution networks. At the same time, the proposed radial constraint processing method effectively enhances the effectiveness of radial topology constraints by gradually identifying loops and paths, reduces the complexity of model solution, improves the flexibility and adaptability of planning, and is suitable for other scenarios that need to consider radial topology. In addition, the introduction of carbon emission reduction factors has promoted the early construction of distributed power sources, met load demand, and reduced carbon emissions. Although it has increased costs in the short term, it will help achieve environmental protection goals and improve economic benefits in the long run.

[0163] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the embodiments disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for multi-stage expansion planning of a distribution network taking into account carbon emission reduction, characterized in that: include: Step 1: Based on the node load and substation capacity in the initial stage, an exponential function is applied to construct a carbon quota quantification model; Step 2: Aiming at the constraints of the radial topology of the distribution network, a method combining incremental ring detection and depth-first search is adopted, and the strategy of disconnection and ring removal is used to determine the constraints suitable for multi-stage expansion planning; Step 3: Based on the carbon quota quantification model and the constraints applicable to the multi-stage expansion planning, a multi-stage expansion planning model including carbon emission costs is constructed; the objective function of the multi-stage expansion planning model is to minimize the sum of construction cost, operation cost and carbon cost, and the constraints of the multi-stage expansion planning model include new construction constraints, flow constraints and radial topology constraints; Step 4: solving the multi-stage extended planning model using second-order cone constraints; The carbon quota quantification model is: In the formula, For the x Annual carbon quota; The initial carbon quota for the distribution network; is the carbon reduction pressure factor of the distribution network; is the total active power load of the distribution network in the first stage; is the total active power capacity of existing substations in the distribution network; is the carbon emissions per unit of active power output; The constraints applicable to the multi-stage expansion plan are: In the formula, is 0 or 1, when t Nodes in the distribution network i and j The line between them has been built. is 1, when the node i and j The line between them has not been built. is 0; 、 Respectively represent t The set of all rings in the distribution network at each stage and the set of paths between all root nodes; Representation Node i and j The lines between For the t Any ring in the distribution network of each stage, is the number of nodes in any ring; For the t Any path between all root nodes in the distribution network of the stage, is the number of nodes in any path; E Represents the set of all lines in the distribution network; For the t The number of all nodes in the distribution network at each stage; For the t The number of all root nodes in the distribution network at each stage.

2. A method for multi-stage expansion planning of a distribution network taking into account carbon emission reduction, characterized in that: include: Step 1: Based on the node load and substation capacity in the initial stage, an exponential function is applied to construct a carbon quota quantification model; Step 2: Aiming at the constraints of the radial topology of the distribution network, a method combining incremental ring detection and depth-first search is adopted, and the strategy of disconnection and ring removal is used to determine the constraints suitable for multi-stage expansion planning; Step 3: Based on the carbon quota quantification model and the constraints applicable to the multi-stage expansion planning, a multi-stage expansion planning model including carbon emission costs is constructed; the objective function of the multi-stage expansion planning model is to minimize the sum of construction cost, operation cost and carbon cost, and the constraints of the multi-stage expansion planning model include new construction constraints, flow constraints and radial topology constraints; Step 4: solving the multi-stage extended planning model using second-order cone constraints; The carbon quota quantification model is: In the formula, For the x Annual carbon quota; The initial carbon quota for the distribution network; is the amplitude of the disturbance term; Fluctuation cycles for short-term impacts; is the carbon reduction pressure factor of the distribution network; is the total active power load of the distribution network in the first stage; is the total active power capacity of existing substations in the distribution network; is the carbon emissions per unit of active power output; The constraints applicable to the multi-stage expansion plan are: In the formula, is 0 or 1, when t Nodes in the distribution network i and j The line between them has been built. is 1, when the node i and j The line between them has not been built. is 0; 、 Respectively represent t The set of all rings in the distribution network at each stage and the set of paths between all root nodes; Representation Node i and j The lines between For the t Any ring in the distribution network of each stage, is the number of nodes in any ring; For the t Any path between all root nodes in the distribution network of the stage, is the number of nodes in any path; E Represents the set of all lines in the distribution network; For the t The number of all nodes in the distribution network at each stage; For the t The number of all root nodes in the distribution network at each stage.

3. The method for multi-stage expansion planning of a distribution network taking into account carbon emission reduction according to claim 2, characterized in that: The step 3 specifically includes: Determining the construction cost, operating cost, and carbon cost of the multi-stage expansion planning model; Constructing the objective function of the multi-stage expansion planning model based on the construction cost, operation cost, carbon cost and carbon quota quantification model; Based on the constraint conditions applicable to the multi-stage expansion planning, the constraint conditions of the multi-stage expansion planning model are determined.

4. The method for multi-stage expansion planning of a distribution network taking into account carbon emission reduction according to claim 3 is characterized in that: The construction costs are: in, For construction costs; The number of stages for planning; is the total number of years in each stage; , , They represent the collection of lines, substations, and distributed generation respectively; , , Respectively t The investment cost of the lines, substations and distributed power sources in each stage; t Nodes in the distribution network i and j The line between them has been built. is 1, when the node i and j The line between them has not been built. is 0; when t Nodes in the distribution network i Substations have been built. is 1, when the node i The substations in the area have not been built. is 0; when t Nodes in the distribution network i Distributed power sources have been built. is 1, when the node i Distributed power generation has not been built. is 0; , , Respectively represent t The construction costs of the lines, substations and distributed generation in each stage; , , are the depreciation coefficients of lines, substations and distributed generation respectively; r is the discount rate; The operating costs are: in, For operating costs; For the t The operating cost of the substation in each stage, is the operating cost of the substation per square unit of energy, Active power generated by the substation; For the t The operating cost of distributed power generation in each stage, is the operating cost of distributed power generation per unit energy squared, The active power generated by distributed power sources; For the t Line network loss costs in each stage, is the unit network loss cost of the line, For Node i and j The resistance of the line between For Node i and j The square of the current in the line between The carbon cost is: in, for carbon costs; For the t Carbon emission cost at each stage; is the carbon trading price, For the t Active power generated by the substation in each stage; is the total number of hours for each phase; For the t The active power generated by the distributed power generation in each stage; Carbon emissions from power generation for distributed power units; For the t The carbon quota of the distribution network in each stage.

5. The method for multi-stage expansion planning of a distribution network taking into account carbon emission reduction according to claim 4, characterized in that: The said t The expression of carbon quota of the distribution network in each stage is: 。 6. The method for multi-stage expansion planning of a distribution network taking carbon emission reduction into account according to claim 5, characterized in that: The newly created constraints are: Among them, when the nodes in the initial state distribution network i and j The line between them has been built. is 1, when the node i and j The line between them has not been built. is 0; when the node in the initial state distribution network i Substations have been built. is 1, when the node i The substations in the area have not been built. is 0; The power flow constraint is: in, For the t Phase Node i Active load; For the t Phase Node i Reactive load; , Respectively t Nodes in the distribution network i, j The square of the voltage amplitude; , Respectively t The flow through the node in the distribution network in the stage i and j Active power and reactive power of the lines between them; , Respectively t The flow through the node in the distribution network in the stage i and k Active power and reactive power of the lines between them; , Node i and j The resistance and reactance of the lines between them; , Node i and k The resistance and reactance of the lines between them; For the t Phases flow through nodes i and j The square of the current amplitude on the line between them; For the t Phases flow through nodes i and k The square of the current amplitude on the line between them; is the set of all nodes; is a maximum positive real number; The radial topology constraints include: Among them, two substations and exist at the same time; For the t Phase Substation and The set of paths between .

7. The method for multi-stage expansion planning of a distribution network taking carbon emission reduction into account according to claim 6, characterized in that: The constraints of the multi-stage expansion planning model also include line power constraints, line capacity limit constraints, and substation output constraints, which are expressed as follows: In the formula, , are the upper and lower limits of the node voltage respectively; Representation Node i and j The square of the maximum current allowed to flow in the line between them; Indicates substation i Rated capacity; Distributed Power i Rated capacity.

8. A multi-stage expansion planning device for a distribution network taking carbon emission reduction into account, characterized in that: include: The first construction unit is used to construct a carbon quota quantification model by applying an exponential function according to the node load and substation capacity in the initial stage; A determination unit is used to determine the constraints applicable to the multi-stage expansion planning by combining incremental ring detection with depth-first search and using the disconnection and ring-breaking strategy for the constraints of the radial topology of the distribution network; A second construction unit is used to construct a multi-stage expansion planning model containing carbon emission costs based on the carbon quota quantification model and the constraints applicable to the multi-stage expansion planning; the objective function of the multi-stage expansion planning model is to minimize the sum of construction cost, operation cost and carbon cost, and the constraints of the multi-stage expansion planning model include new construction constraints, flow constraints and radial topology constraints; A solving unit, used for solving the multi-stage extended planning model using a second-order cone constraint; The carbon quota quantification model is: or, in, In the formula, For the x Annual carbon quota; The initial carbon quota for the distribution network; is the amplitude of the disturbance term; Fluctuation cycles for short-term impacts; is the carbon reduction pressure factor of the distribution network; is the total active power load of the distribution network in the first stage; is the total active power capacity of existing substations in the distribution network; is the carbon emissions per unit of active power output; The constraints applicable to the multi-stage expansion plan are: In the formula, is 0 or 1, when t Nodes in the distribution network i and j The line between them has been built. is 1, when the node i and j The line between them has not been built. is 0; 、 Respectively represent t The set of all rings in the distribution network at each stage and the set of paths between all root nodes; Representation Node i and j The lines between For the t Any ring in the distribution network of each stage, is the number of nodes in any ring; For the t Any path between all root nodes in the distribution network of the stage, is the number of nodes in any path; E Represents the set of all lines in the distribution network; For the t The number of all nodes in the distribution network at each stage; For the t The number of all root nodes in the distribution network at each stage.

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