A method and device for selecting a topology scheme of a collector system in an offshore wind farm

Abstract

The present invention provides a method and device for selecting a topology scheme of a collector system for an offshore wind farm. Each planned cable is obtained based on each cable node within a planned area; the construction cost corresponding to each planned cable for a target voltage level is obtained; based on each cable node and the Clarke - Wright savings algorithm, a ring topology scheme is planned; based on the construction cost, the investment cost corresponding to the ring topology for the target voltage level is calculated; a radial topology scheme is planned using a mathematical optimization model, and based on the construction cost, the investment cost corresponding to the radial topology for the target voltage level is calculated; the optimal topology scheme is determined by comparing the investment cost of the ring topology and the investment cost of the radial topology. In this solution, the investment costs of different collector line topologies at the target voltage level are calculated, the economy and reliability of the topology scheme are weighed, the limitations of subjectively selecting the optimal topology scheme based on experience are effectively avoided, so as to achieve the purpose of improving the selection accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of power system planning, and particularly relates to a method and device for selecting a topology scheme of a collector system for an offshore wind farm. Background Art

[0002] In recent years, offshore wind farms have been continuously developing towards the deep sea and large scale. However, due to various operating conditions and extreme weather in the deep sea area, higher economic and reliability requirements are put forward for offshore wind farms. Therefore, the topology scheme selected for the construction of the collector system at different voltage levels must be considered from the actual situation, overall consideration, and comprehensive weighing of economy and reliability. At present, the topology schemes of the collector system include a radial structure and a ring structure. Among them, the investment cost of the radial structure at the same voltage level is greater than that of the ring structure. However, in terms of reliability, the ring structure is superior to the radial structure.

[0003] In the prior art, the optimal topology scheme for the construction of the collector system at different voltage levels is selected by experts based on subjective experience, and there is a problem of low accuracy. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a method and device for selecting a topology scheme of a collector system for an offshore wind farm to achieve the purpose of improving the accuracy of selecting the optimal topology scheme.

[0005] To achieve the above purpose, embodiments of the present invention provide the following technical solutions:

[0006] A first aspect of an embodiment of the present invention discloses a method for selecting a topology scheme of a collector system for an offshore wind farm, the method including:

[0007] Based on each cable node preset in the planning area, obtain each planned cable in the planning area;

[0008] Obtain the construction cost corresponding to the target voltage level for each of the planned cables;

[0009] Based on each of the cable nodes and the Clarke-Wright savings algorithm, plan to obtain a ring topology scheme;

[0010] Based on the construction costs corresponding to the target voltage level for each of the planned cables in the ring topology scheme, calculate the ring topology investment cost corresponding to the target voltage level;

[0011] Judge whether any two of the planned cables cross. If so, determine the two crossed planned cables as a crossed cable combination, and obtain a plurality of crossed cable combinations;

[0012] Generate crossing constraints based on each of the crossing cable combinations; the crossing constraints characterize that two crossed planned cables in each of the crossing cable combinations are prohibited from being constructed simultaneously;

[0013] Use the constraint conditions to constrain a preset mathematical optimization model; the constraint conditions at least include: the crossing constraints and the radial structure constraints, and the radial structure constraints are used to constrain the topological scheme obtained by planning the mathematical optimization model to be a radial topological scheme; the mathematical optimization model includes:

[0014]

[0015] Among them, the complete directed graph G=(Ψ,L), Ψ={Ψ Sub ,Ψ WT}, Ψ Sub represents the substation nodes among the cable nodes, Ψ WT the fan nodes among the cable nodes, L represents each of the planned cables, L={(i,j)∈Ψ×Ψ:i≠j}, i and j represent two different cable nodes, c ij represents the construction cost corresponding to each of the planned cables for the target voltage level, x ij is the decision variable indicating whether the planned cable between cable node i and cable node j is constructed, and the value of x ij is controlled by the crossing constraints, represents the network loss cost within the operation period of the offshore wind farm, η is the coefficient for converting the power loss at one moment to the power loss within the operation period of the offshore wind farm, r ij is the resistance of the planned cable between cable node i and cable node j, f ij is the active power flowing through cable node i and cable node j, represents the total value of the curtailed wind power generation, represents the curtailed wind power at cable node i;

[0016] Solve the planning of the mathematical optimization model to obtain a radial topological scheme and calculate the radial topological investment cost corresponding to the target voltage level;

[0017] Compare the ring topology investment cost and the radial topology investment cost, and determine the optimal topological scheme corresponding to the target voltage level based on the comparison result.

[0018] Preferably, the obtaining of each planned cable in the planning area based on each cable node preset in the planning area includes:

[0019] For each cable node preset in the planning area, if there are other cable nodes in the planning area whose distance from the cable node is less than a preset distance, a planned cable is obtained through planning between the cable node and the other cable nodes.

[0020] Preferably, the cable nodes include a substation node and a plurality of fan nodes;

[0021] The ring topology scheme obtained through planning based on each of the cable nodes and the Clarke - Wright savings algorithm includes:

[0022] Using the Clarke - Wright savings algorithm, a reference vector at an arbitrary angle is determined with the substation node as the reference point;

[0023] Continuously scan along the clockwise or counter - clockwise direction of the reference vector, add the scanned fan nodes to a preset fan cluster. Whenever the number of fan nodes in the fan cluster reaches a quantity threshold, add the scanned fan nodes to the next fan cluster until there are no fan nodes in the planning area that have not been added to the fan cluster;

[0024] Using the Clarke - Wright savings algorithm to connect the fan nodes in each fan cluster to obtain a ring topology scheme.

[0025] Preferably, the step of using the Clarke - Wright savings algorithm to connect the fan nodes in each fan cluster to obtain a ring topology scheme includes:

[0026] For each fan cluster, extract the corresponding distance matrix and calculate a cost savings matrix based on the distance matrix;

[0027] For each fan cluster, sort the upper - triangular elements in the cost savings matrix corresponding to the fan cluster in descending order to obtain a sorted list and obtain the first element of the sorted list;

[0028] Initialize a pre - created routing sequence based on the first element of the sorted list;

[0029] Search the sorted list in descending order according to the routing sequence to obtain a fan node pair containing two fan nodes, and connect the fan node pair to the end of the routing sequence until the sorted list is searched completely;

[0030] Connect the starting point and the ending point of the routing sequence to the substation node to obtain a closed - loop structure corresponding to the fan cluster;

[0031] Based on the closed - loop structures corresponding to each fan cluster, a ring topology scheme is obtained through planning.

[0032] Preferably, the determining whether any two of the planned cables cross each other includes:

[0033] Select any two of the planned cables from each of the planned cables, and mark them as the first planned cable and the second planned cable respectively;

[0034] Obtain the coordinates of each cable node corresponding to the first planned cable and the second planned cable respectively, and mark them as: W i =(x i , y i ) i ∈ [1, 4];

[0035] Determine whether the coordinates of each cable node satisfy a preset condition; the preset condition includes: Wherein,

[0036] If so, determine that the first planned cable and the second planned cable cross each other;

[0037] If not, determine that the first planned cable and the second planned cable do not cross each other.

[0038] A second aspect of the embodiments of the present invention discloses a device for selecting a topological scheme of a collector system of an offshore wind farm, and the device includes:

[0039] A first obtaining unit, configured to obtain each planned cable in the planned area based on each cable node preset in the planned area;

[0040] A second obtaining unit, configured to obtain the construction cost corresponding to the target voltage level for each planned cable;

[0041] A planning unit, configured to plan a ring topology scheme based on each cable node and the Clarke - Wright savings algorithm;

[0042] A first calculating unit, configured to calculate the investment cost of the ring topology corresponding to the target voltage level based on the construction costs corresponding to the target voltage level of each planned cable in the ring topology scheme;

[0043] A judging unit, configured to judge whether any two of the planned cables cross each other. If so, determine the two crossed planned cables as a crossed cable combination, and obtain a plurality of crossed cable combinations; generate a crossing constraint based on each crossed cable combination; the crossing constraint represents that the two crossed planned cables in each crossed cable combination are prohibited from being constructed simultaneously;

[0044] A second calculation unit is configured to constrain a preset mathematical optimization model by using constraint conditions; the constraint conditions at least include: the cross constraint and the radial structure constraint, and the radial structure constraint is used to constrain the topological scheme obtained by planning the mathematical optimization model to be a radial topological scheme; the mathematical optimization model includes:

[0045]

[0046] Wherein, the complete directed graph G = (Ψ, L), Ψ = {Ψ Sub , Ψ WT}, Ψ Sub represents the substation node among the cable nodes, Ψ WT the fan node among the cable nodes, L represents each planned cable, L = {(i, j) ∈ Ψ × Ψ: i ≠ j}, i and j represent two different cable nodes, c ij represents the construction cost corresponding to the target voltage level of each planned cable, x ij is a decision variable indicating whether the planned cable between cable node i and cable node j is constructed, and the value of x ij is controlled by the cross constraint, represents the network loss cost within the operation period of the offshore wind farm, η is a coefficient for converting the power loss at one moment to the power loss within the operation period of the offshore wind farm, r ij is the resistance of the planned cable between cable node i and cable node j, f ij is the active power flowing through cable node i and cable node j, represents the total value of the curtailed wind power generation, represents the curtailed wind power at cable node i;

[0047] Solve the planning of the mathematical optimization model to obtain a radial topological scheme and calculate the radial topological investment cost corresponding to the target voltage level;

[0048] A comparison unit compares the ring topology investment cost and the radial topology investment cost, and determines the optimal topological scheme corresponding to the target voltage level based on the comparison result.

[0049] Preferably, the first acquisition unit is specifically configured to:

[0050] For each cable node preset in the planning area in advance, if there is another cable node in the planning area whose distance from the cable node is less than a preset distance, then plan a planned cable between the cable node and the other cable node.

[0051] Preferably, the cable nodes include substation nodes and multiple fan nodes;

[0052] The planning unit includes:

[0053] A determination subunit, configured to use the Clarke - Wright savings algorithm to determine a reference vector at any angle with the substation node as the reference point;

[0054] A scanning subunit, which continuously scans along the clockwise or counterclockwise direction of the reference vector, adds the scanned fan nodes to a preset fan cluster, and whenever the number of fan nodes in the fan cluster reaches a quantity threshold, adds the scanned fan nodes to the next fan cluster until there are no fan nodes in the planning area that have not been added to the fan cluster;

[0055] A connection subunit, configured to use the Clarke - Wright savings algorithm to connect the fan nodes in each fan cluster to obtain a ring topology scheme.

[0056] Preferably, the connection subunit is specifically configured to:

[0057] For each fan cluster, extract the corresponding distance matrix and calculate a cost savings matrix based on the distance matrix;

[0058] For each fan cluster, sort the upper triangular elements in the cost savings matrix corresponding to the fan cluster in descending order to obtain a sorted list and obtain the first element of the sorted list;

[0059] Initialize a pre - created routing sequence based on the first element of the sorted list;

[0060] Search the sorted list in descending order according to the routing sequence to obtain a fan node pair including two fan nodes, and connect the fan node pair to the end of the routing sequence until the sorted list is searched completely;

[0061] Connect the starting point and the ending point of the routing sequence to the substation node to obtain a closed - loop structure corresponding to the fan cluster;

[0062] Based on the closed - loop structures corresponding to each fan cluster, plan to obtain a ring topology scheme.

[0063] Based on the method and device for selecting a topology scheme of a collector system for an offshore wind farm provided in the embodiments of the present invention, based on each cable node preset in a planning area, each planned cable in the planning area is obtained; the construction cost corresponding to a target voltage level for each of the planned cables is obtained; based on each of the cable nodes and the Clarke-Wright savings algorithm, a ring topology scheme is planned; based on the construction costs corresponding to the target voltage level for each of the planned cables in the ring topology scheme, the investment cost of the ring topology corresponding to the target voltage level is calculated; it is determined whether any two of the planned cables cross, and if so, the two crossed planned cables are determined as a crossed cable combination, and multiple crossed cable combinations are obtained; a crossing constraint is generated based on each of the crossed cable combinations; the crossing constraint indicates that the two crossed planned cables in each of the crossed cable combinations are prohibited from being constructed simultaneously; using a preset mathematical optimization model, each of the cable nodes and the crossing constraint, a radial topology scheme is planned, and based on the construction costs corresponding to the target voltage level for each of the planned cables in the radial topology scheme, the investment cost of the radial topology corresponding to the target voltage level is calculated; the investment cost of the ring topology and the investment cost of the radial topology are compared, and based on the comparison result, the optimal topology scheme corresponding to the target voltage level is determined. In this solution, the investment costs of different collector line topology structures at the target voltage level are calculated, the economy and reliability of the topology scheme are weighed, the limitation of subjectively selecting the optimal topology scheme by experience is effectively avoided, so as to achieve the purpose of improving the selection accuracy rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without creative efforts.

[0065] Figure 1 Schematic diagrams of various topology structures of the collector system disclosed in the embodiments of the present invention;

[0066] Figure 2 Flowchart of a method for selecting a topology scheme of a collector system for an offshore wind farm disclosed in the embodiments of the present invention;

[0067] Figure 3 Schematic diagram of obtaining a planned cable disclosed in the embodiments of the present invention;

[0068] Figure 4 Schematic diagram of dividing a wind turbine cluster disclosed in the embodiments of the present invention;

[0069] Figure 5 Schematic diagram of cost-saving calculation disclosed in an embodiment of the present invention;

[0070] Figure 6 Example diagram for judging cross cables disclosed in an embodiment of the present invention;

[0071] Figure 7 Structural diagram of a device for selecting a topology scheme of a collector system in an offshore wind farm disclosed in an embodiment of the present invention. Detailed implementation manners

[0072] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0073] In this application, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0074] As Figure 1 shown, schematic diagrams of various topology structures of the collector system disclosed in an embodiment of the present invention.

[0075] Among them, the topology structure of the collector system includes a ring topology structure and a radial topology structure, and the ring topology structure is further subdivided into a single-sided ring topology structure and a double-sided ring topology structure.

[0076] It should be noted that the radial topology structure is relatively simple and has a low investment cost, but its reliability is poor. Once a line fails, all the wind turbines on the feeder where the line is located will lose power supply. On the contrary, the ring topology structure has redundancy, so the reliability of the collector system with the ring topology structure is relatively high. At the same time, the problem is that the required investment cost is relatively high.

[0077] As Figure 2 shown, a flowchart of a method for selecting a topology scheme of a collector system in an offshore wind farm disclosed in an embodiment of the present invention mainly includes the following steps:

[0078] Step S1: Based on each cable node preset in the planned area, obtain each planned cable in the planned area.

[0079] It should be noted that the planning of an offshore wind farm generally includes the following sequence: macro-site selection, micro-site selection, collector system planning, and transmission system planning. In this application, after micro-site selection, the planning area is determined, and then the collector system planning is carried out within the planning area. After the planning area is determined, all cable nodes within the planning area are known information.

[0080] Cable nodes include: fan nodes and substation nodes, and each cable node has a corresponding coordinate.

[0081] In the specific implementation process of step S1, for each cable node preset in the planning area in advance, if there are other cable nodes in the planning area whose distance from the cable node is less than the preset distance, then a planned cable is obtained through planning between the cable node and the other cable nodes.

[0082] More specifically, the cable nodes include multiple fan nodes and substation nodes to obtain the preset distance, and determine all the planned cables between adjacent fan nodes (taking any fan node as the center of a circle and the preset distance as the radius to draw a circle, and all fan nodes within the circle are regarded as adjacent fan nodes) and between it and the substation nodes.

[0083] As Figure 3 shown, it is a schematic diagram of obtaining a planned cable disclosed in an embodiment of the present invention.

[0084] For cable node 1, draw a circle with the preset distance. Cable nodes 2, 3, 5, 6, and 7 are within the range of this circle, while cable nodes 4 and 8 are outside the circle range. Therefore, the cables between cable node 1 and 4, and cable node 1 and 8 are not used as planned cables, and the cables between cable node 1 and 2, cable node 1 and 3, cable node 1 and 5, cable node 1 and 6, and cable node 1 and 7 are used as planned cables.

[0085] And so on, draw circles with all cable nodes such as cable node 2 and cable node 3 as the centers of the circles in turn, and all candidate cables within the preset distance are used as planned cables.

[0086] In one embodiment, the length of the planned cable can be unrestricted by the preset distance.

[0087] Step S2: Obtain the construction cost corresponding to each planned cable for the target voltage level.

[0088] In step S2, the target voltage level is obtained by the user's selection from multiple voltage levels. That is to say, assuming that the user needs to calculate the optimal topology scheme corresponding to a certain voltage level, then this voltage level is used as the target voltage level.

[0089] It should be noted that the voltage levels of the mainstream current collector systems for offshore wind farms are concentrated on two options: 35 kV and 66 kV. For an offshore wind farm with the same installed capacity, the 66 kV current collector system requires less inter-array wiring and theoretically has a lower construction cost compared to the 35 kV current collector system.

[0090] It can be understood that the construction costs of the planned cables corresponding to different voltage levels are also different, and due to factors such as length among the planned cables, the construction costs are also different.

[0091] In the specific implementation process of step S2, according to the current market price, determine the construction cost corresponding to each planned cable for the target voltage level.

[0092] Step S3: Based on each cable node and the Clarke-Wright savings algorithm, plan to obtain a ring topology scheme.

[0093] In step S3, the Clarke-Wright savings algorithm is specifically the improved two-stage Clarke-Wright savings algorithm (Clark and Wright’s Savings, CWS), which adopts a parallel descent matching mechanism to avoid the possible situation of missing cable nodes or sub-optimal paths.

[0094] The execution process of the CWS algorithm includes two stages. In the first stage, according to the line transmission capacity, divide the fan nodes into multiple preset fan clusters. In the second stage, within each fan cluster, use the improved CWS algorithm to connect the fan nodes to form a closed-loop structure.

[0095] It should be noted that the line transmission capacity stipulates that the number of fan nodes in each fan cluster cannot exceed the quantity threshold.

[0096] Among them, the cable nodes include a substation node and multiple fan nodes. The specific implementation process of step S3 includes the following steps:

[0097] Step S31: Use the Clarke-Wright savings algorithm to determine a reference vector at any angle with the substation node as the reference point.

[0098] As Figure 4 shown, it is a schematic diagram of dividing fan clusters disclosed in an embodiment of the present invention.

[0099] Step S32: Continuously scan along the clockwise or counterclockwise direction of the reference vector, add the scanned fan nodes to the preset fan clusters. Whenever the number of fan nodes in a fan cluster reaches the quantity threshold, add the scanned fan nodes to the next fan cluster until there are no fan nodes in the planned area that have not been added to the fan clusters.

[0100] It should be noted that whenever the number of fan nodes in a fan cluster reaches the quantity threshold, it indicates that the total capacity in the fan cluster reaches the default cable transmission capacity limit.

[0101] Step S33: Connect the fan nodes in each fan cluster using the Clarke - Wright savings algorithm to obtain a ring topology scheme.

[0102] In the specific implementation process of step S33, it includes the following steps:

[0103] Step S331: For each fan cluster, extract the corresponding distance matrix and calculate the cost savings matrix based on the distance matrix.

[0104] In the specific implementation process of step S331, extract the distance matrix D of each fan cluster from the distance matrix D l , according to the distance matrix D l , calculate the cost savings matrix S of each fan cluster l .

[0105] Among them, the distance matrix D is calculated from the distances between sample points in the original dataset, that is, calculated according to the distances between each cable node in the planned area.

[0106] Step S332: For each fan cluster, sort the upper triangular elements in the cost savings matrix corresponding to the fan cluster in descending order to obtain a sorted list and obtain the first element of the sorted list.

[0107] As Figure 5 shown, it is a schematic diagram of cost savings calculation disclosed in an embodiment of the present invention.

[0108] Specifically, for each fan cluster, sort the upper triangular elements of the cost savings matrix S l corresponding to the fan cluster in descending order to obtain a sorted list and obtain the first element of the sorted list

[0109] Among them, the calculation method of is o represents the substation node, d l represents the element in the distance matrix D l .

[0110] Step S333: Initialize the pre - created routing sequence based on the first element of the sorted list.

[0111] In step S333, initialize the routing sequence R based on the first element of the sorted list n , denoted as (i, j).

[0112] Step S334: Search the sorted list in descending order according to the routing sequence to obtain a fan node pairing containing two fan nodes, and connect the fan node pairing to the end of the routing sequence until the sorted list is searched completely.

[0113] In step S334, search down the sorted list according to the current routing sequence (i, j), and find the next pair of fan node pairings (i k , j k ), where i k and j k are the same as a point in R n . If multiple eligible fan node pairings are found, select the first pairing at the top of the sorted list, and connect the fan node pairing (i k , j k ) to the end of the current routing sequence R n .

[0114] Step S335: Connect the starting point and the ending point of the routing sequence to the substation node to obtain a closed-loop structure corresponding to the fan cluster, and based on the closed-loop structures corresponding to each fan cluster, plan to obtain a ring topology scheme.

[0115] In step S355, connect the substation node to the starting point and the ending point of the routing sequence R n to form a closed-loop structure.

[0116] Step S4: Calculate the ring topology investment cost corresponding to the target voltage level based on the construction costs of the planned cables corresponding to the target voltage level in the ring topology scheme.

[0117] In the specific implementation process of step S4, accumulate the construction costs of the planned cables corresponding to the target voltage level in the ring topology scheme to obtain the ring topology investment cost corresponding to the target voltage level.

[0118] Step S5: Determine whether any two planned cables cross. If so, determine the two crossed planned cables as a crossed cable combination, obtain multiple crossed cable combinations, and generate crossing constraints based on each crossed cable combination.

[0119] In step S5, the crossing constraint indicates that the two crossed planned cables in each crossed cable combination are prohibited from being constructed simultaneously.

[0120] Among them, the specific implementation process of determining whether any two planned cables cross is as follows:

[0121] Select any two planned cables from each planned cable, and mark them as the first planned cable and the second planned cable respectively; obtain the coordinates of each cable node corresponding to the first planned cable and the second planned cable respectively, and mark them as: Wi =(x i , y i ) for i ∈ [1, 4];

[0122] Judge whether the coordinates of each cable node meet the preset conditions:

[0123]

[0124] Among them,

[0125] If so, determine that the first planned cable and the second planned cable cross; if not, determine that the first planned cable and the second planned cable do not cross.

[0126] As Figure 6 shown, it is an example diagram of cross - cable judgment disclosed in the embodiment of the present invention.

[0127] Exemplarily, set the coordinates of four fan nodes to be W i =(x i , y i ) for i ∈ [1, 4].

[0128] Judge whether the planned cables W 1 W 2 and the planned cables W 3 W 4 cross:

[0129]

[0130] When α, β ∈ [0, 1], it is considered that the planned cables W 1 W 2 and the planned cables W 3 W 4 cross, forming a cross - cable combination, and add the cross - cable combination to L CAC , where L CAC represents the set of all cross - cable combinations that occur. Add the cross - cable combination to the set L CAC , specifically:

[0131]

[0132] Exemplarily, the process of generating cross - constraints based on each cross - cable combination is as follows:

[0133] Set x ij to be a binary variable indicating whether the planned cable (i, j) between cable nodes i and j is invested and constructed. When x ij is 1, it means that the planned cable (i, j) is constructed. For all cross - cable combinations in L CAC , make x 12+x 34 If ≤ 1, the cross - constraint is:

[0134] x AB +x CD ≤ 1

[0135] This equation indicates that the planned cables AB and CD cannot be built simultaneously in the final planning result, and this cross - constraint applies to all cross - cable combinations in L CAC .

[0136] Step S6: Using the preset mathematical optimization model, each cable node, and the cross - constraint, plan to obtain a radial topology scheme, and calculate the radial topology investment cost corresponding to the target voltage level based on the construction cost of each planned cable in the radial topology scheme corresponding to the target voltage level.

[0137] In the specific implementation process of step S6, the preset mathematical optimization model is constrained by the constraint conditions; the constraint conditions at least include: cross - constraint and radial structure constraint, and the radial structure constraint is used to constrain the topology scheme planned by the mathematical optimization model to be a radial topology scheme; the mathematical optimization model includes:

[0138]

[0139] Among them, the complete directed graph G=(Ψ, L), Ψ = {Ψ Sub , Ψ WT}; Ψ Sub represents the substation node in the cable nodes, and Ψ WT represents the fan node in the cable nodes.

[0140] L represents each planned cable, L = {(i, j) ∈ Ψ×Ψ: i≠j}, where i and j represent two different cable nodes, c ij represents the construction cost of each planned cable corresponding to the target voltage level, x ij is the decision variable indicating whether the planned cable between cable node i and cable node j is built, and the value of x ij is controlled by the cross - constraint.

[0141] represents the total cost of network loss during the operation period of the offshore wind farm. η is the coefficient for converting the power loss at one moment to the power loss during the operation period of the offshore wind farm, and its calculation is η = planned years × full - load hours per year. r ij is the resistance of the planned cable between cable node i and cable node j, and f ij is the active power flowing through cable nodes i and j.

[0142] represents the total value of the curtailed wind power generation. Denotes the wind power loss at cable node i.

[0143] It should be noted that the mathematical optimization model aims to minimize the construction cost of the collector system cables, the network loss cost and the wind power loss cost during the entire life cycle of the offshore wind farm. Usually, by setting M, the wind power loss during normal operation is not allowed to take non-zero values.

[0144] Specifically, the radial structure constraints include:

[0145]

[0146] Constraints (1)-(6) are operation constraints. Constraint (1) is the cable power limit, constraint (2) is the power balance KCL constraint, and S represents the section association matrix. Constraint (3) is the large M constraint for applying KVL, and constraint (4) represents the voltage limit constraint. Constraint (5) means that the un-supplied power of each fan cannot exceed its generated power, and constraint (6) ensures the tree-shaped planning result, and its root node is the substation node. Constraints (7)-(9) are spanning tree constraints to ensure that the planning result is a radial topological structure.

[0147] In one embodiment, due to the low reliability of the radial topological structure, the interruption probability and the mean time to repair (MTTR) of the submarine cable need to be considered, and the reliability-related cost is introduced into the mathematical optimization model.

[0148] That is, C EENG = Pr ele ·MTTR·py·fr·∑ (,j)∈L l ij x ij P ij . Among them, C EENG represents the cost related to EENG, Pr ele is the price of wind energy (unit: ￥ / MWh), MTTR is the mean time to repair (unit: hours), py is the life of the offshore wind farm (unit: years), fr represents the failure rate of the cables in the offshore wind farm (unit: times / km / hour), and l ij represents the length of the planned cable (i,j). Therefore, fr∑ (,j)∈L l ij x ij P ij represents EENG, and the corresponding power transmitted in each cable is P ij .

[0149] Solve the mathematical optimization model planning to obtain the radial topological scheme and calculate the investment cost of the radial topology corresponding to the target voltage level.

[0150] The specific implementation process of the solution includes: in the MATLAB software, by using the modeling tool YALMIP to establish a mathematical optimization model and calling commercial solvers such as Gurobi or CPLEX, the mathematical model can be solved to obtain the radial topology investment cost corresponding to the target voltage level.

[0151] Step S7: Compare the loop topology investment cost and the radial topology investment cost, and determine the optimal topology scheme corresponding to the target voltage level based on the comparison result.

[0152] In one embodiment, compare the loop topology investment cost and the radial topology investment cost, and select the scheme with the lower cost as the optimal topology scheme for the target voltage level.

[0153] Based on the method for selecting a topology scheme of a marine wind farm power collection system disclosed in the above embodiments of the present invention, based on each cable node preset in the planning area, each planned cable in the planning area is obtained; the construction cost corresponding to the target voltage level of each planned cable is obtained; based on each cable node and the Clarke - Wright savings algorithm, a loop topology scheme is planned; based on the construction costs corresponding to the target voltage level of each planned cable in the loop topology scheme, the loop topology investment cost corresponding to the target voltage level is calculated; it is judged whether any two planned cables cross, and if so, the two crossed planned cables are determined as a crossed cable combination, and multiple crossed cable combinations are obtained; cross constraints are generated based on each crossed cable combination; the cross constraints represent that the two crossed planned cables in each crossed cable combination are prohibited from being constructed simultaneously; using a preset mathematical optimization model, each cable node and the cross constraints, a radial topology scheme is planned, and based on the construction costs corresponding to the target voltage level of each planned cable in the radial topology scheme, the radial topology investment cost corresponding to the target voltage level is calculated; compare the loop topology investment cost and the radial topology investment cost, and determine the optimal topology scheme corresponding to the target voltage level based on the comparison result. In this solution, the investment costs of different power collection line topologies at the target voltage level are calculated, the economy and reliability of the topology scheme are weighed, the limitations of subjectively selecting the optimal topology scheme based on experience are effectively avoided, so as to achieve the purpose of improving the selection accuracy.

[0154] Corresponding to the method for selecting a topology scheme of a marine wind farm power collection system disclosed in the above embodiments of the present invention, as Figure 7 shown, it is a structural diagram of a device for selecting a topology scheme of a marine wind farm power collection system disclosed in an embodiment of the present invention.

[0155] The device includes: a first acquisition unit 701, a second acquisition unit 702, a planning unit 703, a first calculation unit 704, a judgment unit 705, a second calculation unit 706, and a comparison unit 707.

[0156] The first acquisition unit 701 is configured to obtain each planned cable in the planned area based on each cable node preset in the planned area.

[0157] The second acquisition unit 702 is configured to obtain the construction cost corresponding to the target voltage level for each planned cable.

[0158] The planning unit 703 is configured to plan a loop topology scheme based on each cable node and the Clarke - Wright savings algorithm.

[0159] The first calculation unit 704 is configured to calculate the loop topology investment cost corresponding to the target voltage level based on the construction cost corresponding to the target voltage level for each planned cable in the loop topology scheme.

[0160] The judgment unit 705 is configured to judge whether any two planned cables cross. If so, determine the two crossed planned cables as a crossed cable combination, and obtain multiple crossed cable combinations; generate crossing constraints based on each crossed cable combination; the crossing constraints indicate that the two crossed planned cables in each crossed cable combination are prohibited from being constructed simultaneously.

[0161] The second calculation unit 706 is configured to use a preset mathematical optimization model, each cable node, and the crossing constraints to plan a radial topology scheme, and calculate the radial topology investment cost corresponding to the target voltage level based on the construction cost corresponding to the target voltage level for each planned cable in the radial topology scheme.

[0162] The comparison unit 704 compares the loop topology investment cost and the radial topology investment cost, and determines the optimal topology scheme corresponding to the target voltage level based on the comparison result.

[0163] Preferably, the first acquisition unit 701 is specifically configured to:

[0164] For each cable node preset in the planned area, if there are other cable nodes in the planned area whose distance from the cable node is less than a preset distance, then plan a planned cable between the cable node and the other cable nodes.

[0165] Preferably, the cable nodes include substation nodes and multiple fan nodes; the planning unit 703 includes:

[0166] A determination subunit is configured to use the Clarke - Wright savings algorithm to determine a reference vector at any angle with the substation node as a reference point.

[0167] The scanning subunit continuously scans in the clockwise or counterclockwise direction along the reference vector, adds the scanned wind turbine nodes to a preset wind turbine cluster, and whenever the number of wind turbine nodes in the wind turbine cluster reaches the quantity threshold, adds the scanned wind turbine nodes to the next wind turbine cluster until there are no wind turbine nodes in the planned area that have not been added to the wind turbine cluster;

[0168] The connection subunit is used to connect the wind turbine nodes in each wind turbine cluster by using the Clarke - Wright savings algorithm to obtain a ring topology scheme.

[0169] Preferably, the connection subunit is specifically used for:

[0170] For each wind turbine cluster, extract the corresponding distance matrix and calculate the cost savings matrix based on the distance matrix;

[0171] For each wind turbine cluster, sort the upper triangular elements in the cost savings matrix corresponding to the wind turbine cluster in descending order to obtain a sorted list and obtain the first element of the sorted list;

[0172] Initialize the pre - created routing sequence based on the first element of the sorted list;

[0173] Search the sorted list in descending order according to the routing sequence to obtain a pairing of wind turbine nodes containing two wind turbine nodes, and connect the pairing of wind turbine nodes to the end of the routing sequence until the sorted list is searched completely;

[0174] Connect the starting point and the ending point of the routing sequence to the substation node to obtain a closed - loop structure corresponding to the wind turbine cluster;

[0175] Based on the closed - loop structures corresponding to each wind turbine cluster, plan to obtain a ring topology scheme.

[0176] Preferably, the judgment unit 705 is specifically used for:

[0177] Select any two planned cables from each planned cable and mark them as the first planned cable and the second planned cable respectively;

[0178] Obtain the coordinates of each cable node corresponding to the first planned cable and the second planned cable respectively and mark them as: W i =(x i ,y i )i∈[1,4];

[0179] Judge whether the coordinates of each cable node meet the preset conditions; the preset conditions include:

[0180] Among them,

[0181] If so, determine that the first planned cable and the second planned cable cross;

[0182] If not, it is determined that the first planned cable and the second planned cable do not cross.

[0183] Preferably, the second calculation unit 706 is specifically configured to:

[0184] Use the constraint conditions to constrain a preset mathematical optimization model; the constraint conditions at least include: crossing constraints and radial structure constraints, and the radial structure constraints are used to constrain the topological scheme planned by the mathematical optimization model to be a radial topological scheme; the mathematical optimization model includes:

[0185]

[0186] Among them, the complete directed graph G = (Ψ, L), Ψ = {Ψ Sub , Ψ WT}}, Ψ Sub represents the substation node among the cable nodes, Ψ WT the fan node among the cable nodes, L represents each planned cable, L = {(i, j) ∈ Ψ × Ψ: i ≠ j}, i and j represent two different cable nodes, c ij represents the construction cost corresponding to the target voltage level of each planned cable, x ij is the decision variable of whether the planned cable between cable node i and cable node j is constructed, and the value of x ij is controlled by the crossing constraint, represents the network loss cost within the operation period of the offshore wind farm, η is the coefficient for converting the power loss at one moment to the power loss within the operation period of the offshore wind farm, r ij is the resistance of the planned cable between cable node i and cable node j, f ij is the active power flowing through cable node i and cable node j, represents the total value of the curtailed wind power generation, represents the curtailed wind power at cable node i;

[0187] Solve the mathematical optimization model planning to obtain a radial topological scheme and calculate the radial topological investment cost corresponding to the target voltage level.

[0188] Based on the method for selecting a topology scheme of a collector system for an offshore wind farm disclosed in the above embodiments of the present invention, based on each cable node preset in the planned area, each planned cable in the planned area is obtained; the construction cost corresponding to the target voltage level of each planned cable is obtained; based on each cable node and the Clarke-Wright savings algorithm, a loop topology scheme is planned; based on the construction costs corresponding to the target voltage level of each planned cable in the loop topology scheme, the loop topology investment cost corresponding to the target voltage level is calculated; it is determined whether any two planned cables cross, and if so, the two crossed planned cables are determined as a crossed cable combination, and multiple crossed cable combinations are obtained; cross constraints are generated based on each crossed cable combination; the cross constraints represent that the two crossed planned cables in each crossed cable combination are prohibited from being constructed simultaneously; using a preset mathematical optimization model, each cable node and the cross constraints, a radial topology scheme is planned, and based on the construction costs corresponding to the target voltage level of each planned cable in the radial topology scheme, the radial topology investment cost corresponding to the target voltage level is calculated; the loop topology investment cost and the radial topology investment cost are compared, and based on the comparison result, the optimal topology scheme corresponding to the target voltage level is determined. In this solution, the investment costs of different collector line topology structures at the target voltage level are calculated, the economy and reliability of the topology scheme are weighed, the limitations of subjectively selecting the optimal topology scheme based on experience are effectively avoided, so as to achieve the purpose of improving the selection accuracy.

[0189] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the differences between each embodiment and other embodiments are emphasized. In particular, for a system or a system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without creative efforts.

[0190] Those skilled in the art may further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0191] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for selecting a topology scheme for an offshore wind farm power collection system, characterized in that: The method comprises: Based on each cable node pre-set in the planning area, obtaining each planned cable in the planning area; Obtaining the construction cost of each of the planned cables corresponding to the target voltage level; Based on each of the cable nodes and the Clark-White economy algorithm, a ring topology solution is planned; Based on the construction cost of each of the planned cables in the ring topology solution corresponding to the target voltage level, the ring topology investment cost corresponding to the target voltage level is calculated; Determine whether any two of the planned cables are crossed, and if so, determine that the two crossed planned cables are a crossover cable combination, and obtain a plurality of crossover cable combinations; Generate a cross constraint based on each cross cable combination; the cross constraint indicates that two cross planned cables in each cross cable combination are prohibited from being constructed at the same time; The preset mathematical optimization model is constrained by using constraint conditions; the constraint conditions at least include: the cross constraint and the radial structure constraint, the radial structure constraint is used to constrain the topology scheme obtained by the mathematical optimization model planning to be a radial topology scheme; the mathematical optimization model includes: Among them, the complete directed graph G = (Ψ, L), Ψ = {Ψ Sub ,Ψ WT },Ψ Sub represents the substation node in the cable node, Ψ WT The wind turbine node in the cable node, L represents each of the planned cables, L = {(i, j)∈Ψ×Ψ:i≠j}, i and j represent two different cable nodes, c ij represents the construction cost of each planned cable corresponding to the target voltage level, x ij is the decision variable for whether the planned cable between cable node i and cable node j is to be constructed, x ij The value of is controlled by the cross constraint, represents the network loss cost within the operating life of the offshore wind farm, η is the coefficient for converting the power loss at a certain moment to the power loss within the operating life of the offshore wind farm, and r ij is the resistance of the planned cable between cable node i and cable node j, f ij is the active power flowing through cable node i and cable node j, represents the total value of curtailed wind power generation, represents the wind power lost at cable node i; Solving the mathematical optimization model planning, obtaining a radial topology solution and calculating the radial topology investment cost corresponding to the target voltage level; The ring topology investment cost and the radial topology investment cost are compared, and based on the comparison result, an optimal topology solution corresponding to the target voltage level is determined.

2. The method according to claim 1, characterized in that The acquiring of each planned cable in the planning area based on each cable node pre-set in the planning area includes: For each cable node pre-set in the planning area, if there are other cable nodes in the planning area whose distance from the cable node is less than the preset distance, planning is performed between the cable node and the other cable nodes to obtain a planned cable.

3. The method according to claim 1, characterized in that The cable node includes a substation node and a plurality of wind turbine nodes; The ring topology solution is planned based on each of the cable nodes and the Clark-White economy algorithm, including: Using the Clark-White economy algorithm, the substation node is used as a reference point to determine a reference vector of any angle; Continuously scanning in a clockwise or counterclockwise direction along the reference vector, adding the scanned wind turbine nodes to a preset wind turbine cluster, and whenever the number of wind turbine nodes in the wind turbine cluster reaches a threshold number, adding the scanned wind turbine nodes to the next wind turbine cluster, until there are no wind turbine nodes that have not been added to the wind turbine cluster in the planning area; The wind turbine nodes in each wind turbine cluster are connected using the Clark-White economy algorithm to obtain a ring topology solution.

4. The method according to claim 3, characterized in that The method of connecting the wind turbine nodes in each wind turbine cluster using the Clark-White saving algorithm to obtain a ring topology solution includes: For each wind turbine cluster, extract a corresponding distance matrix and calculate a cost saving matrix based on the distance matrix; For each of the wind turbine clusters, arranging the upper triangular elements in the cost saving matrix corresponding to the wind turbine cluster in descending order to obtain a sorted list and obtaining the first element of the sorted list; Initialize a pre-created routing sequence based on the first element of the sorted list; Searching the sorted list in descending order according to the routing sequence to obtain a wind turbine node pairing including two wind turbine nodes, and connecting the wind turbine node pairing to the end of the routing sequence until the sorted list is completely searched; Connecting the starting point and the end point of the routing sequence to the substation node to obtain a closed-loop structure corresponding to the wind turbine cluster; Based on the closed-loop structures corresponding to the wind turbine clusters, a ring topology solution is planned.

5. The method according to claim 1, characterized in that The determining whether any two planned cables cross each other includes: Select two of the planned cables from the planned cables and mark them as the first planned cable and the second planned cable respectively; The coordinates of the cable nodes corresponding to the first planned cable and the second planned cable are obtained respectively, and marked as: W i =(x i ,y i )i∈[1,4]; Determine whether the coordinates of each of the cable nodes meet preset conditions; the preset conditions include: in, If so, determining that the first planned cable and the second planned cable cross; If not, it is determined that the first planned cable and the second planned cable do not cross.

6. A device for selecting a topology scheme for an offshore wind farm power collection system, characterized in that: The device comprises: A first acquisition unit, configured to acquire each planned cable in the planning area based on each cable node pre-set in the planning area; A second acquisition unit is used to acquire the construction cost of each of the planned cables corresponding to the target voltage level; A planning unit, used for planning a ring topology solution based on each of the cable nodes and the Clark-White economy algorithm; A first calculation unit is used to calculate the ring topology investment cost corresponding to the target voltage level based on the construction cost of each of the planned cables in the ring topology solution corresponding to the target voltage level; A judging unit is used to judge whether any two of the planned cables cross, and if so, determine that the two crossed planned cables are a cross cable combination, and obtain a plurality of cross cable combinations; generate a cross constraint based on each of the cross cable combinations; the cross constraint indicates that the two crossed planned cables in each of the cross cable combinations are prohibited from being constructed at the same time; The second calculation unit is used to constrain the preset mathematical optimization model by using constraint conditions; the constraint conditions at least include: the cross constraint and the radial structure constraint, the radial structure constraint is used to constrain the topology scheme obtained by the mathematical optimization model to be a radial topology scheme; the mathematical optimization model includes: Among them, the complete directed graph G = (Ψ, L), Ψ = {Ψ Sub ,Ψ WT },Ψ Sub represents the substation node in the cable node, Ψ WT The wind turbine node in the cable node, L represents each of the planned cables, L = {(i, j)∈Ψ×Ψ:i≠j}, i and j represent two different cable nodes, c ij represents the construction cost of each planned cable corresponding to the target voltage level, x ij is the decision variable for whether the planned cable between cable node i and cable node j is to be constructed, x ij The value of is controlled by the cross constraint, represents the network loss cost within the operating life of the offshore wind farm, η is the coefficient for converting the power loss at a certain moment to the power loss within the operating life of the offshore wind farm, and r ij is the resistance of the planned cable between cable node i and cable node j, f ij is the active power flowing through cable node i and cable node j, represents the total value of curtailed wind power generation, represents the wind power lost at cable node i; Solving the mathematical optimization model planning, obtaining a radial topology solution and calculating the radial topology investment cost corresponding to the target voltage level; A comparison unit compares the ring topology investment cost with the radial topology investment cost, and determines an optimal topology solution corresponding to the target voltage level based on the comparison result.

7. The device according to claim 6, characterized in that The first acquisition unit is specifically used to: For each cable node pre-set in the planning area, if there are other cable nodes in the planning area whose distance from the cable node is less than the preset distance, planning is performed between the cable node and the other cable nodes to obtain a planned cable.

8. The device according to claim 6, characterized in that The cable node includes a substation node and a plurality of wind turbine nodes; The planning unit comprises: A determination subunit, used to determine a reference vector of any angle using the Clark-White economy algorithm with the substation node as a reference point; A scanning subunit continuously scans in a clockwise or counterclockwise direction along the reference vector, and adds the scanned wind turbine nodes to a preset wind turbine cluster, and whenever the number of wind turbine nodes in the wind turbine cluster reaches a number threshold, adds the scanned wind turbine nodes to the next wind turbine cluster, until there are no wind turbine nodes that have not been added to the wind turbine cluster in the planning area; The connection subunit is used to connect the wind turbine nodes in each wind turbine cluster using the Clark-White economy algorithm to obtain a ring topology solution.

9. The device according to claim 8, characterized in that The connecting subunit is specifically used for: For each wind turbine cluster, extract a corresponding distance matrix and calculate a cost saving matrix based on the distance matrix; For each of the wind turbine clusters, arranging the upper triangular elements in the cost saving matrix corresponding to the wind turbine cluster in descending order to obtain a sorted list and obtaining the first element of the sorted list; Initialize a pre-created routing sequence based on the first element of the sorted list; Searching the sorted list in descending order according to the routing sequence to obtain a wind turbine node pairing including two wind turbine nodes, and connecting the wind turbine node pairing to the end of the routing sequence until the sorted list is completely searched; Connecting the starting point and the end point of the routing sequence to the substation node to obtain a closed-loop structure corresponding to the wind turbine cluster; Based on the closed-loop structures corresponding to the wind turbine clusters, a ring topology solution is planned.

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