A method and system for optimizing candidate sets for transmission planning based on redundant constraint identification

Abstract

The present invention discloses a method and system for optimizing a transmission planning candidate set based on redundant constraint identification. The method is used to obtain a minimum-scale candidate line set that meets planning requirements, thereby reducing the solution space for subsequent calculations of transmission network planning problems and improving computational efficiency. First, the grid connectivity is checked. Then, based on the redundant constraint identification method, lines are added to the test grid to obtain an initial optimized candidate line set. Finally, based on the redundant constraint identification method, lines are reduced and corrected to the test grid to obtain a minimum-scale transmission planning candidate line set. The present invention does not require additional optimization problems to be solved and is highly efficient for formulating candidate line sets for complex, large-scale power system transmission planning.

Description

Technical Field

[0001] The present invention belongs to the technical field of power transmission network planning, and in particular relates to a method and system for optimizing a transmission planning candidate set based on redundant constraint identification. Background Art

[0002] With the dual carbon goals being put forward, the power system is undergoing an energy transformation. The large-scale integration of renewable energy sources, such as wind power and photovoltaics, has necessitated an urgent need for transmission network planning to ensure the system can accommodate a high proportion of renewable energy. For provincial power systems, the sheer scale of their grids and the sheer number of components involved significantly complicates transmission network planning.

[0003] Most research on transmission network planning focuses on improving the computational efficiency of planning models, while little attention has been paid to the optimization of candidate line sets. For provincial-level power systems, the size of the candidate line set can be quite large. If the initial candidate line set could be screened and optimized to obtain the minimum candidate line set that meets planning requirements, without solving additional optimization problems, computational efficiency could be improved at the source.

[0004] The purpose of transmission expansion planning is to alleviate grid congestion by building lines, thereby ensuring power delivery and load supply. Therefore, the key to selecting a set of candidate lines is to ensure that the construction of the candidate lines can effectively reduce the overload risk of the power system. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned existing technologies and provide a method and system for optimizing the transmission planning candidate set based on redundant constraint identification, which is used to obtain the minimum-scale candidate line set that meets the planning requirements, thereby reducing the solution space for the calculation of subsequent transmission network planning problems and improving calculation efficiency.

[0006] The present invention adopts the following technical solutions:

[0007] A method for selecting a candidate set for transmission planning based on redundant constraint identification includes the following steps:

[0008] S1. Obtain the system power planning plan, the load level for the planned year, the existing transmission network and network parameters, the initial set of candidate lines, and the parameters of the candidate lines;

[0009] S2. Check the connectivity of the existing network frame. If the connectivity is satisfied, initialize the test network frame to the existing network frame, end step S2, and execute step S3;

[0010] S3. Redundancy constraint identification and calculation are performed on the test grid. If the test grid does not have an overload risk, the overall calculation process is terminated, the power supply planning scheme and load level are re-established, and the line addition process based on redundancy constraint identification is completed.

[0011] S4. For the test grid obtained by the line addition process in step S3, the candidate lines included in the transmission corridors without overload risk are deleted, and redundant constraint identification calculations are performed to ensure that no new transmission corridors with overload risk appear in the test grid after the lines are deleted. This is done until no more qualified lines can be deleted, completing the optimization of the transmission planning candidate set.

[0012] Specifically, step S2 is as follows:

[0013] S201, check the connectivity of the existing network frame. If the connectivity is not satisfied, execute step S202;

[0014] S202: Check the connectivity of the entire grid. If the connectivity is satisfied, proceed to step S203; otherwise, terminate the overall calculation process, the given initial candidate line set is unqualified, and a new initial candidate line set is formulated;

[0015] S203 , initializing the test grid to an existing grid, selecting lines from the initial candidate line set, and adding them to the test line set until the test grid meets connectivity requirements.

[0016] Furthermore, in step S202, let the test circuit set be Determine the system node set Ω B With the test circuit set Ω L Is the network topology connected?

[0017] If connected, the entire grid meets connectivity requirements, and step S203 is executed to begin adding lines to the existing grid to obtain a set of test lines with connectivity. If not connected, there is a problem with the complete set of candidate lines, and the overall calculation process ends. The given initial candidate line set fails, and island information is output. The initial candidate line set is then redefined based on the island information.

[0018] Furthermore, step S203 is specifically as follows:

[0019] S2031, the existing grid of the system is used as the main system, and the node set included in the main system is Ω B,0 , the remaining isolated systems are regarded as subsystems, and the node set in subsystem i is Ω B,i ;

[0020] S2032, traverse subsystem i, in the set Find the candidate route in the node set Ω B,i The nodes in the main system and the node set Ω B,0Or subsystem j node set Ω B,j The middle nodes are connected, j≠i, and the line with the lowest construction cost is selected from the eligible lines l i ,make

[0021] S2033, after the traversal of the subsystem in step S2032 is completed, Re-judge Ω B and Ω L The connectivity of the network topology is checked. If it is connected, the current test network meets the connectivity check and starts to identify redundancy constraints. If it is not connected, the main system node set Ω is updated. B,0 and the node set Ω of each subsystem B,i , return to execute step S2032.

[0022] Specifically, step S3 is as follows:

[0023] S301, perform redundancy constraint identification calculation on the test grid, and if the test grid has an overload risk, execute step S302;

[0024] S302: Select lines from the candidate line set and add them to the test line set, and perform redundancy constraint identification calculation until the test grid has no overload risk or no lines meeting the conditions exist in the candidate line set.

[0025] Furthermore, in step S301, Identify redundant constraints on a connected test grid:

[0026] If the test grid does not have an overload risk, the total calculation process ends and the power planning scheme and load level are corrected; if the test grid has an overload risk, for the transmission corridors included in the test grid, the set of transmission corridors with overload risk is set to Ω LC,1 , the set of transmission corridors without overload risk is Ω LC,2 , the node set of the transmission corridor with overload risk is Ω B,1 .

[0027] Furthermore, when judging the lines of the entire grid, line l j The forward power constraint is F G′(j) P G′ ≤γ j , the negative power constraint is F G′(NG′+j) P G′ ≤γ NG′+j If both constraints are judged to be redundant, then line l j There is no risk of overload; otherwise, the line l j There is a risk of overloading.

[0028] Furthermore, step S302 is specifically as follows:

[0029] S3021, from the test candidate line set Find a line that satisfies the following conditions: a) There is a node at one end that belongs to the set Ω B,1 , b) The transmission corridor where the line is located does not belong to Ω LC,2 ;

[0030] S3022. If there is a line that meets the conditions, select the line l with the cheapest construction cost from all the lines that meet the conditions, and let Ω L =Ω L ∪{l}, for the updated test grid, redundancy constraint identification calculation is re-performed to update Ω LC,1 ,Ω LC,2 and Ω B,1 ;like If the test grid no longer faces overload risk, step S302 ends; otherwise, step S3021 continues.

[0031] S3023. If no line that meets the conditions exists, the line adding process is terminated and the test grid is marked as being at risk of overload.

[0032] Specifically, step S4 is as follows:

[0033] S401, Order The set of transmission corridors with overload risk is Ω LC,1 , the set of transmission corridors without overload risk is Ω LC,2 , the set of candidate lines deleted during the line reduction process is exist The corridor selected belongs to Ω LC,2 All the lines of Ω constitute the set L′ ;

[0034] S402, if From Ω L′ Select the line l with the highest construction cost, let Ω L =Ω L \{l}, redundancy constraints are re-identified for the test grid, and the set of transmission corridors with overload risk is obtained as Ω LC′,1 and the set of transmission corridors without overload risk Ω LC′,2 ;

[0035] like Delete the line, Ω LC,1 =Ω LC′,1 ,Ω LC,2 =Ω LC′,2, continue to execute step S401; do not delete the line, let Ω L =Ω L ∪{l},Ω L′ =Ω L′ \{l}; if Continue to execute step S402, otherwise execute step S403;

[0036] S403, if End the total calculation process, let Output the optimal candidate route set.

[0037] Another technical solution of the present invention is a system for optimizing a transmission planning candidate set based on redundant constraint identification, comprising:

[0038] The acquisition module obtains the system power planning plan, the load level for the planned year, the existing transmission network and network parameters, the initial set of candidate lines, and the parameters of the candidate lines;

[0039] The initialization module checks the connectivity of the existing network. If the connectivity is met, the test network is initialized to the existing network. The initialization module ends and the line addition module is executed.

[0040] The line adding module performs redundant constraint identification and calculation on the test grid. If the test grid does not have overload risk, the overall calculation process ends, the power supply planning scheme and load level are re-established, and the line adding process based on redundant constraint identification is completed.

[0041] The line reduction module removes the candidate lines contained in the transmission corridors without overload risks from the test grid obtained by the line addition module, and performs redundant constraint identification calculations. It must ensure that no new transmission corridors with overload risks appear in the test grid after the line removal. This is done until there are no more eligible lines to be removed, completing the optimization of the transmission planning candidate set.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] The present invention provides a method for optimizing a transmission planning candidate set based on redundant constraint identification. Given a known power source planning scheme and load level, as well as an initial candidate line set, the method optimizes the initial candidate line set based on the transmission network redundant constraint identification method without requiring additional optimization problems to ultimately obtain a minimum-scale candidate line set that meets planning requirements. This set can provide more streamlined boundary conditions for subsequent grid planning problem calculations. By further solving the grid planning problem, the optimal line construction set is obtained. The method theoretically solves the problem of how to select a transmission planning candidate line set, and can significantly improve the computational efficiency of solving grid planning problems from the source.

[0044] Furthermore, checking the connectivity of the existing grid is a necessary step for executing subsequent calculation processes. If the grid is not connected, it is impossible to use the redundant constraint identification method to calculate whether the grid is at risk of overload. Therefore, it is necessary to ensure that the grid used in subsequent tests meets the connectivity requirements.

[0045] Furthermore, the connectivity of the entire grid is checked. This is only performed when the existing grid connectivity is not satisfied. This step is used to verify the eligibility of the initial candidate line set. If the connectivity of the entire grid is not satisfied, the initial candidate line set is unqualified and must be reset.

[0046] Furthermore, when the existing grid is not connected but the entire grid is connected, lines are added to the test line set to obtain a test grid with connectivity. This step is used to ensure that the redundant constraint identification method can be used normally in subsequent steps.

[0047] Furthermore, by executing the line adding process of step S3, a preliminary set of candidate planning routes that meet the planning requirements can be obtained, thereby providing boundary conditions for the subsequent line reducing process.

[0048] Furthermore, in step S301, redundant constraint identification and calculation are performed on the test grid. This redundant constraint identification method is the core algorithm of the present invention, and all subsequent processes will be based on this redundant constraint identification method. If the connected test grid does not have an overload risk, it indicates that the installed power supply or load level is too low, and the current grid does not need to be expanded. It is necessary to verify the installed power supply and load levels.

[0049] Furthermore, for line l j The forward power constraint F G′(j) P G′ ≤γ j and negative power constraint F G′(NG′+j) P G′ ≤γ NG′+j If both constraints are judged to be redundant, then line l j There is no risk of overload; otherwise, the line l j There is an overload risk. This step is to determine whether there is an overload risk on the transmission line after executing the redundant constraint identification method. It is a necessary step required in the subsequent line addition and removal process.

[0050] Furthermore, step S302, which adds lines to the test line set based on the redundant constraint identification method, is a key step in the present invention for screening the optimal candidate line set. Based on the economic efficiency of the candidate lines, the most economical line among the qualified lines is preferentially selected, and ultimately a preliminarily optimized candidate line set can be obtained.

[0051] Furthermore, step S4, which uses a redundant constraint identification method to reduce the number of test line sets, is a correction step in selecting the optimal candidate line set. This process results in a larger initial optimized candidate line set due to the selection of a small number of lines that are not necessarily expanded. This step eliminates lines from corridors within the test grid that pose no risk of overload, ensuring a minimum candidate line set that meets planning requirements.

[0052] In summary, the method of the present invention can obtain the minimum-scale candidate line set that meets planning requirements, does not require a solution process for the optimization problem, and is suitable for reducing the solution space for the calculation of subsequent transmission network planning problems and improving calculation efficiency.

[0053] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the process of the present invention;

[0055] Figure 2 A flow chart of the entire transmission planning process;

[0056] Figure 3 There is a grid diagram for the six-node system. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0058] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0059] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0060] It should be further understood that the term "and / or" as used in the present specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items. For example, A and / or B may represent: A alone, A and B simultaneously, or B alone. In addition, the character " / " herein generally indicates that the associated items are in an "or" relationship.

[0061] It should be understood that although the terms "first," "second," and "third" may be used to describe preset ranges in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are merely used to distinguish one preset range from another. For example, without departing from the scope of embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0062] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0063] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0064] The present invention provides a method for optimizing a transmission planning candidate set based on redundant constraint identification. This method is used to obtain a minimum-scale candidate line set that meets planning requirements, thereby narrowing the solution space for subsequent transmission network planning calculations and improving computational efficiency. First, grid connectivity is checked. Then, based on the redundant constraint identification method, lines are added to the test grid to obtain an initial optimized candidate line set. Finally, based on the redundant constraint identification method, lines are removed from the test grid to obtain a minimum-scale transmission planning candidate line set. This method does not require additional optimization problems to be solved and is highly efficient for developing candidate line sets for transmission planning in complex, large-scale power systems.

[0065] See also Figure 1 The present invention provides a method for selecting a transmission planning candidate set based on redundant constraint identification, comprising the following steps:

[0066] S1. Obtain basic technical data of the system from the power system planning department;

[0067] The basic technical data of the system include: system power planning scheme, load level in the planning year, existing transmission network and network parameters, initial set of candidate lines and parameters of the candidate lines.

[0068] S2. Check network connectivity, including the following steps:

[0069] S201, check the connectivity of the existing network frame. If the connectivity is satisfied, initialize the test network frame to the existing network frame, end step S2, and execute step S3; otherwise, continue to execute step S202;

[0070] Test circuit collection:

[0071] A set of circuits used for performing redundant constraint identification testing in the calculation process of the present invention;

[0072] Test candidate line set:

[0073] The candidate line set used in the calculation process of the present invention is the optimal candidate line set after the calculation process is completed.

[0074] Existing grid:

[0075] A network consisting of a collection of system nodes and a collection of existing lines;

[0076] Test grid:

[0077] A network consisting of a collection of system nodes and a collection of test lines;

[0078] Full grid:

[0079] The network consists of a set of system nodes and an initial set of candidate lines.

[0080] The set of system nodes is Ω B , the existing line set in the system is The initial candidate line set is The test circuit set is Ω L , the test candidate line set is The optimal candidate route set is

[0081] Set the test circuit set to Determine the system node set Ω B With the test circuit set Ω L Whether the constructed network topology is connected.

[0082] S202: Check the connectivity of the entire grid. If the connectivity is satisfied, proceed to step S203; otherwise, terminate the overall calculation process, and the given initial candidate line set is unqualified, requiring a new initial candidate line set to be formulated.

[0083] Set the test circuit set to Determine the system node set Ω B With the test circuit set Ω L Is the network topology connected?

[0084] If connected, the entire grid meets the connectivity requirements, and step S203 is executed to start adding lines on the basis of the existing grid to obtain a set of test lines with connectivity;

[0085] If not, there is a problem with the set complete candidate route set, the total calculation process ends, the given initial candidate route set is unqualified, the island information is output, and the initial candidate route set is re-formulated based on the island information.

[0086] S203 , initializing the test grid to an existing grid, selecting lines from the initial candidate line set, and adding them to the test line set until the test grid meets connectivity requirements.

[0087] Assume that the set of candidate routes that ensure connectivity is initialization

[0088] S2031, the existing grid of the system is used as the main system, and the node set included in the main system is Ω B,0 , the remaining isolated systems are regarded as subsystems, where the node set in subsystem i is Ω B,i ;

[0089] S2032, traverse subsystem i, in the set Find the candidate line in Ω B,i The nodes in the main system node set Ω B,0 Or subsystem j node set Ω B,j (j≠i) The nodes are connected, and the line with the lowest construction cost is selected from the eligible lines. i ,make

[0090] S2033, after the traversal subsystem is completed, set Re-judge Ω B and Ω L If the network topology is connected, the current test grid has met the connectivity check, and step S203 is ended, and redundancy constraint identification is started; if it is not connected, the main system node set Ω is updated. B,0 and the node set Ω of each subsystem B,i , return to execute step S2032.

[0091] S3, the line adding process based on redundant constraint identification, includes the following steps:

[0092] S301: Perform redundancy constraint identification calculation on the test grid. If the test grid does not have overload risk, the total calculation process ends and the formulated power supply planning scheme and load level are unreasonable, requiring a new power supply planning scheme and load level. Otherwise, proceed to step S302.

[0093] Place Identify redundant constraints on a connected test grid:

[0094] If the test grid does not have an overload risk, it means that the power supply capacity or load level is too low. The total calculation process ends and the power supply planning scheme and load level need to be revised.

[0095] If the test grid has an overload risk, for the transmission corridors included in the test grid (the number of lines in the corridor is not 0), the set of transmission corridors with overload risk is set to Ω LC,1 , the set of transmission corridors without overload risk is Ω LC,2 , the node set of the transmission corridor with overload risk is Ω B,1 , continue to step S302.

[0096] The principle of the redundant constraint identification method is as follows:

[0097] (1) Network constraint form

[0098] Considering a power system containing conventional power sources, new energy sources, and energy storage, its network security constraints are written as:

[0099]

[0100] Among them, NG / NR / NS / ND / NL are the number of conventional units / loads / transmission lines included in the system grid; are the transfer distribution factors of conventional units / new energy units / energy storage / load i on the lth transmission line respectively; are the power of conventional units / new energy units / energy storage / load i respectively; is the upper limit of the transmittable active power of the lth transmission line (thermal stability limit).

[0101] Write the network security constraints in matrix form:

[0102] F G P G +F R P R +F S P S -FD P D ≤Γ (2)

[0103]

[0104]

[0105] For F R / F S / F D and P E / P S / P D , just follow F G and P G Just replace the subscript and subscript indexes accordingly.

[0106]

[0107] (2) Constructing a linear programming problem

[0108] Construct a linear programming problem to maximize the maximum power that can flow through the line in one direction while ensuring the power balance of the system. Select the jth column of the expression on the left side of the network security constraint as the objective function term, then the linear programming problem can be written as follows:

[0109]

[0110] in, are the installed capacity of conventional units / new energy i respectively; is the installed power generation capacity of energy storage unit i; Take a negative value for the charging installed capacity of energy storage unit i; are the maximum / minimum power of load i respectively.

[0111] The optimal value of the above linear programming problem represents the maximum power that can flow in a single direction through the line corresponding to the jth column of the network security constraint while ensuring system power balance. All power sources have output ranges determined by their installed capacity, while the load power range is determined by the maximum and minimum values ​​that they can achieve. Therefore, the following criteria are obtained:

[0112] If the optimal value of the objective function in problem (6) satisfies W j * ≤γ j , then the constraint F G(j) P G +F R(j) P R +F S(j) P S -F D(j) P D ≤γ jThat is a redundant constraint, where F G(j) , F R(j) , F S(j) , F D(j) , γ j P G , P R , P S , P D , the j-th row element in Γ.

[0113] (3) Simplified linear programming problem

[0114] All units and loads are combined and collectively referred to as equivalent power sources, where the loads can be regarded as power sources with negative generating power, and the number of equivalent power sources is recorded as NG′.

[0115] Then problem (6) is equivalent to:

[0116]

[0117] Among them, F G′(j) is the jth row of the transfer distribution factor matrix of the equivalent power source for the transmission line; P G′ is the power vector of the equivalent power supply; is the power of equivalent power source i; is the maximum / minimum power of the equivalent power supply i.

[0118] The criterion is simplified to: If the optimal value of the objective function of problem (7) satisfies W j * ≤γ j , then the constraint F G′(j) P G′ ≤γ j This is a redundant constraint.

[0119] (4) Derivation of the optimal solution form

[0120] For the linear programming problem (7), according to its constraints, the range of the sum of equivalent power is:

[0121]

[0122] Therefore, the necessary and sufficient conditions for the problem to have a feasible solution are:

[0123]

[0124] First, F G′(j) The element f in l,i To sort, use index g m Replace index i so that:

[0125]

[0126] If constraint (9) holds, there exists an integer k∈[1,NG′] such that:

[0127]

[0128] Right now:

[0129]

[0130] Obviously, there is a feasible solution to this problem:

[0131]

[0132] That is, it satisfies:

[0133]

[0134] Now we prove that formula (13) is the optimal solution to problem (7). The Lagrangian function of problem (7) is:

[0135]

[0136] The dual problem of problem (7) is expressed as:

[0137]

[0138] According to the duality theory, the optimal value of the objective function of problem (16) is not less than the optimal value of the objective function of problem (7), that is:

[0139]

[0140] Pick Then we have:

[0141]

[0142]

[0143] It is easy to conclude that formula (13) is the optimal solution of formula (18), namely:

[0144]

[0145] Then it satisfies

[0146]

[0147] According to formulas (14), (17) and (21), we can get:

[0148]

[0149] therefore

[0150]

[0151] According to the duality principle, equation (13) is the optimal solution to the original problem (7).

[0152] (5) Network constraint redundancy criterion

[0153] If there exists an integer k∈[1,NG′] such that

[0154]

[0155] If it holds, then F G′(j) P G′ ≤γ j This is a redundant constraint.

[0156] When judging the lines of the entire grid, the line l j For example, its forward power constraint is F G′(j) P G′ ≤γ j , the negative power constraint is F G′(NG′+j) P G′ ≤γ NG′+j If both constraints are judged to be redundant, then line l j There is no risk of overload; otherwise, the line l j There is a risk of overloading.

[0157] S302: Select lines from the candidate line set and add them to the test line set, and perform redundancy constraint identification calculation until the test grid has no overload risk or no lines meeting the conditions exist in the candidate line set.

[0158] Assume that the candidate line set selected by the line adding process based on redundant constraint identification is initialization

[0159] S3021, from the test candidate line set Find a line that satisfies the following conditions: a) There is a node at one end that belongs to the set Ω B,1 , b) The transmission corridor where the line is located does not belong to Ω LC,2 ;

[0160] S3022. If there is a line that meets the conditions, select the line with the cheapest construction cost from all the lines that meet the conditions, and set Ω L =Ω L ∪{l}. For the updated test grid, redundancy constraint identification calculation is performed again to update Ω LC,1 ,Ω LC,2 and Ω B,1 .like If the test grid no longer faces overload risk, step S302 ends; otherwise, step S3021 continues.

[0161] S3023. If no line that meets the conditions exists, the line adding process is terminated and the test grid is marked as being at risk of overload.

[0162] S4. Line reduction process based on redundant constraint identification

[0163] For the test grid obtained during the line addition process, the candidate lines included in the transmission corridors without overload risk are deleted, and redundant constraint identification calculations are performed to ensure that no new transmission corridors with overload risk appear in the test grid after the lines are deleted, until there are no eligible lines to be deleted.

[0164] Place The set of transmission corridors with overload risk is Ω LC,1 , the set of transmission corridors without overload risk is Ω LC,2 . Let the set of candidate lines to be deleted during the line reduction process be initialization

[0165] S401, in order to ensure that the line deletion process does not destroy the connectivity of the test network, The corridor selected belongs to Ω LC,2 All the lines of Ω constitute the set L′ ;

[0166] S402, if From Ω L′ Select the line l with the highest construction cost, and set Ω L =Ω L \{l}, redundancy constraints are re-identified for the test grid, and the set of transmission corridors with overload risk is obtained as Ω LC′,1 and the set of transmission corridors without overload risk Ω LC′,2 ;

[0167] like This means that after deleting the line, there is no overload risk in the new transmission corridor of the test grid. The line can be deleted. Ω LC,1 =Ω LC′,1 ,Ω LC,2 =Ω LC′,2 , continue to step S401.

[0168] Otherwise, it means that deleting the line will cause a new transmission corridor with overload risk to appear in the test grid. The line cannot be deleted. L =Ω L ∪{l},Ω L′ =ΩL′ \{l}; if Continue to execute step S402; otherwise, execute step S403.

[0169] S403, if End the total calculation process and set Output the optimal candidate route set.

[0170] In another embodiment of the present invention, a transmission planning candidate set optimization system based on redundant constraint identification is provided. The system can be used to implement the above-mentioned transmission planning candidate set optimization method based on redundant constraint identification. Specifically, the transmission planning candidate set optimization system based on redundant constraint identification includes an acquisition module, an initial module, a line addition module and a line reduction module.

[0171] The acquisition module obtains the system power planning plan, the load level in the planning year, the existing transmission network and network parameters, the initial set of candidate lines and the parameters of the candidate lines;

[0172] The initialization module checks the connectivity of the existing network. If the connectivity is met, the test network is initialized to the existing network. The initialization module ends and the line addition module is executed.

[0173] The line adding module performs redundant constraint identification and calculation on the test grid. If the test grid does not have overload risk, the overall calculation process ends, the power supply planning scheme and load level are re-established, and the line adding process based on redundant constraint identification is completed.

[0174] The line reduction module removes the candidate lines contained in the transmission corridors without overload risks from the test grid obtained by the line addition module, and performs redundant constraint identification calculations. It must ensure that no new transmission corridors with overload risks appear in the test grid after the line removal. This is done until there are no more eligible lines to be removed, completing the optimization of the transmission planning candidate set.

[0175] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0176] Case Analysis

[0177] In order to verify the effectiveness of the method proposed in this invention, a 6-node system was selected for calculation and analysis. The system has a grid structure as follows Figure 3 As shown, node B6 in the system is an island node, and the existing grid does not meet connectivity requirements. Nodes B1 and B3 have conventional units of 200MW and 400MW respectively; nodes B2 and B4 each have a 400MW renewable energy unit. There are 6 transmission corridors in the existing grid, and each corridor has only one line. Given the initial candidate line set, each corridor between nodes is allowed to build a line, that is, a total of 15 expandable transmission corridors, and the maximum number of lines allowed for each transmission corridor is 3, that is, the initial candidate line set has a total of 39 lines. Design comparison example:

[0178] Example 1: Directly based on the initial candidate route set Calculate the power grid planning problem and obtain the optimal line construction set Ω L,1 ;

[0179] Example 2: First, the optimal candidate line set is obtained by using the transmission planning candidate line set optimization method in the present invention. Then calculate the power grid planning problem and get the optimal line construction set Ω L,2 .

[0180] The specific calculation results are shown in Table 1.

[0181] Table 1 Optimal candidate line set

[0182]

[0183]

[0184] After calculation, the calculation result is Ω L,1 =Ω L,2 , proving that the method of the present invention can effectively screen out the optimal lines for investment and construction; in the optimal candidate line set obtained in Example 2, only 17 lines remain, which is more than half of the initial candidate line set. Example 1 takes 679 seconds, and Example 2 takes 279 seconds, proving that the method of the present invention can greatly improve the computational efficiency of power grid planning problems.

[0185] In summary, the present invention's method and system for selecting a transmission planning candidate set based on redundant constraint identification offer greater applicability. Compared to traditional methods that require solving optimization problems, the present invention employs a heuristic approach, first checking grid connectivity, then adding lines to the test grid based on the redundant constraint identification method to obtain an initial optimized candidate set. Finally, the test grid is corrected by removing lines based on the redundant constraint identification method, thereby obtaining a minimum-scale transmission planning candidate set. This method eliminates the need for solving additional optimization problems and is highly efficient for developing candidate sets for transmission planning in complex, large-scale power systems.

[0186] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0187] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0188] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0189] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0190] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for optimizing a candidate set for transmission planning based on redundant constraint identification, characterized in that: The following steps are involved: S1. Obtain the system power planning plan, the load level for the planned year, the existing transmission network and network parameters, the initial set of candidate lines, and the parameters of the candidate lines; S2. Check the connectivity of the existing network frame. If the connectivity is satisfied, initialize the test network frame to the existing network frame, end step S2, and execute step S3, which is specifically: S201, check the connectivity of the existing network frame. If the connectivity is not satisfied, execute step S202; S202: Check the connectivity of the entire grid. If the connectivity is satisfied, proceed to step S203; otherwise, terminate the overall calculation process, the given initial candidate line set is unqualified, and a new initial candidate line set is formulated; S203: Initialize the test grid to an existing grid, select lines from the initial candidate line set, and add them to the test line set until the test grid meets the connectivity requirements. Specifically: S2031, the existing grid of the system is used as the main system, and the node set included in the main system is , the remaining isolated systems are regarded as subsystems, subsystems The set of midpoints is ; S2032, traversal subsystem , in the collection Find the candidate route in the node set The nodes in the main system node set or subsystem Node Collection The middle nodes are connected, , select the line with the lowest construction cost from the eligible lines ,make , ; S2033, after the traversal of the subsystem in step S2032 is completed, , re-judge and The connectivity of the constructed network topology. If it is connected, the current test network meets the connectivity check and starts to identify redundant constraints; if it is not connected, the main system node set is updated and each subsystem node set , return to step S2032; S3. Redundancy constraint identification and calculation are performed on the test grid. If the test grid does not have an overload risk, the overall calculation process is terminated, the power supply planning scheme and load level are re-established, and the line addition process based on redundancy constraint identification is completed. Specifically, S301, perform redundancy constraint identification calculation on the test grid, and if the test grid has an overload risk, execute step S302; S302: Select lines from the candidate line set and add them to the test line set, and perform redundancy constraint identification calculations until the test grid is free of overload risk or no lines meeting the conditions exist in the candidate line set; S4. For the test grid obtained by the line addition process in step S3, the candidate lines included in the transmission corridors without overload risk are deleted, and redundant constraint identification calculations are performed to ensure that no new transmission corridors with overload risk appear in the test grid after the lines are deleted. This is done until no eligible lines can be deleted, and the selection of the transmission planning candidate set is completed. Specifically, the following steps are performed: S401, Order , the set of transmission corridors with overload risk is , the set of transmission corridors without overload risk is , the set of candidate lines deleted during the line reduction process is ,exist The corridor where you select belongs to All lines of ; S402, if ,from Select the route with the highest construction cost ,make , redundancy constraint identification is performed on the test grid again, and the set of transmission corridors with overload risk is obtained as and the set of transmission corridors without overload risk ; like , delete the line, and let , , , continue to execute step S401; do not delete the line, let , ;like Continue to execute step S402, otherwise execute step S403; S403, if , end the total calculation process, let , output the optimal candidate route set.

2. The method for optimizing the transmission planning candidate set based on redundant constraint identification according to claim 1, characterized in that: In step S202, let the test circuit set be , determine the system node set With test circuit assembly Is the network topology connected? If connected, the entire grid meets the connectivity requirements, and step S203 is executed to start adding lines on the basis of the existing grid to obtain a set of test lines with connectivity; If not, there is a problem with the set complete candidate route set, the total calculation process ends, the given initial candidate route set is unqualified, the island information is output, and the initial candidate route set is re-formulated based on the island information.

3. The method for optimizing the candidate set for transmission planning based on redundant constraint identification according to claim 1, characterized in that: In step S301, , redundancy constraint identification for the test grid with connectivity: If the test grid does not have an overload risk, the total calculation process ends and the power planning scheme and load level are corrected; if the test grid has an overload risk, for the transmission corridors included in the test grid, the set of transmission corridors with overload risk is set to , the set of transmission corridors without overload risk is , the node set of the transmission corridor with overload risk is .

4. The method for optimizing the transmission planning candidate set based on redundant constraint identification according to claim 3, characterized in that: When judging the lines of the entire grid, the lines The forward power constraint is , the negative power constraint is If both constraints are judged to be redundant, the line There is no risk of overloading; otherwise, the line There is a risk of overloading.

5. The method for optimizing the candidate set for transmission planning based on redundant constraint identification according to claim 1, characterized in that: Step S302 is specifically as follows: S3021, from the test candidate line set Find the circuit that meets the following conditions: a) There is an end node that belongs to the set , b) The transmission corridor where the line is located does not belong to ; S3022. If there are any eligible routes, select the one with the cheapest construction cost from all eligible routes. ,make , , , for the updated test grid, redundancy constraint identification calculation is re-performed and updated , and ;like , the test grid no longer has an overload risk, and step S302 ends; Otherwise, continue to step S3021; S3023. If no line that meets the conditions exists, the line adding process is terminated and the test grid is marked as being at risk of overload.

6. A transmission planning candidate set optimization system based on redundant constraint identification, characterized in that: include: The acquisition module obtains the system power planning plan, the load level for the planned year, the existing transmission network and network parameters, the initial set of candidate lines, and the parameters of the candidate lines; The initialization module checks the connectivity of the existing network. If the connectivity is met, the test network is initialized to the existing network. The initialization module ends and the line addition module is executed. Specifically: S201, check the connectivity of the existing network frame. If the connectivity is not satisfied, execute step S202; S202: Check the connectivity of the entire grid. If the connectivity is satisfied, proceed to step S203; otherwise, terminate the overall calculation process, the given initial candidate line set is unqualified, and a new initial candidate line set is formulated; S203: Initialize the test grid to an existing grid, select lines from the initial candidate line set, and add them to the test line set until the test grid meets the connectivity requirements. Specifically: S2031, the existing grid of the system is used as the main system, and the node set included in the main system is , the remaining isolated systems are regarded as subsystems, subsystems The set of midpoints is ; S2032, traversal subsystem , in the collection Find the candidate route in the node set The nodes in the main system node set or subsystem Node Collection The middle nodes are connected, , select the line with the lowest construction cost from the eligible lines ,make , ; S2033, after the traversal of the subsystem in step S2032 is completed, , re-judge and The connectivity of the constructed network topology. If it is connected, the current test network meets the connectivity check and starts to identify redundant constraints; If not connected, update the main system node set and each subsystem node set , return to step S2032; The line adding module performs redundant constraint identification and calculation on the test grid. If the test grid does not have overload risk, the overall calculation process ends, the power supply planning scheme and load level are re-established, and the line adding process based on redundant constraint identification is completed. Specifically: S301, perform redundancy constraint identification calculation on the test grid, and if the test grid has an overload risk, execute step S302; S302: Select lines from the candidate line set and add them to the test line set, and perform redundancy constraint identification calculations until the test grid is free of overload risk or no lines meeting the conditions exist in the candidate line set; The line reduction module removes candidate lines from transmission corridors without overload risks in the test grid obtained by the line addition module, and performs redundant constraint identification calculations to ensure that no new transmission corridors with overload risks appear in the test grid after the line removal. This process continues until no more qualified lines can be removed, completing the optimization of the transmission planning candidate set. Specifically, S401, Order , the set of transmission corridors with overload risk is , the set of transmission corridors without overload risk is , the set of candidate lines deleted during the line reduction process is ,exist The corridor where you select belongs to All lines of ; S402, if ,from Select the route with the highest construction cost ,make , redundancy constraint identification is performed on the test grid again, and the set of transmission corridors with overload risk is obtained as and the set of transmission corridors without overload risk ; like , delete the line, and let , , , continue to execute step S401; do not delete the line, let , ;like Continue to execute step S402, otherwise execute step S403; S403, if , end the total calculation process, let , output the optimal candidate route set.

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