Offshore wind power reactive compensation configuration method and system

Abstract

The invention belongs to the technical field of wind power generation, and particularly relates to an offshore wind power reactive power compensation configuration method and system.The configuration method comprises the steps that a reactive power compensation configuration model of an offshore wind power plant is built, and the joints of a current collection circuit of the offshore wind power plant and all draught fans are connected into a reactive power compensation configuration model; the joint of a sending-out submarine cable of the offshore wind plant and the onshore centralized control center is used as a node; calculating a network loss allocation coefficient of each node of the wind power plant by using the reactive compensation configuration model, and obtaining a preset installation node of a reactive compensation device of the wind power plant; and under a full-power working condition, taking the reactive power compensation configuration capacity of each preset installation node as a control variable, taking the minimum set network loss target parameter value as an optimization target, and combining the set constraint conditions to construct an offshore wind power reactive power compensation configuration model, and solving the model through the optimal power flow to obtain the reactive power compensation configuration of the offshore wind power. And obtaining the optimal reactive compensation capacity corresponding to each preset installation node.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and in particular relates to a method and system for configuring reactive power compensation for offshore wind power. Background Art

[0002] During the operation of offshore wind farms, a large amount of power loss will occur. The average annual power loss accounts for about 3% to 5% of its total power generation. The existence of these additional power losses seriously restricts the power generation efficiency and economic benefits of offshore wind farms. The collection lines and transmission cables of offshore wind farms generally use AC submarine cables. When operating, AC submarine cables not only generate large charging power, which leads to increased network losses of offshore wind farms and occupies line capacity (compared with the common overhead lines in onshore AC power grids, the ground capacitance of AC submarine cables is 15 to 20 times that of overhead lines of the same voltage level, but its series impedance is 0.5 to 1 times that of overhead lines of the same voltage level. As the transmission distance of AC submarine cables continues to increase, it will cause a large surplus of charging power of AC submarine cables), but also cause power frequency overvoltage problems, which seriously threaten the safe operation of equipment. Therefore, it is necessary to configure reactive power compensation for the offshore wind farm access system to meet the requirements of reactive local balance, power frequency overvoltage control and voltage control during operation.

[0003] At present, the traditional reactive power compensation method for offshore wind power is to place high-voltage reactors in the onshore centralized control center or offshore substation to absorb the reactive power of the AC submarine cable, reduce the network loss of the offshore wind farm, and improve the utilization rate of the submarine cable capacity. However, the traditional reactive power compensation method for offshore wind power usually cannot balance the capacitive reactive power of the field on site, which makes the line loss in the field too large, the power frequency overvoltage too high, affects the safe use of the equipment, and cannot fully reduce the network loss of the offshore wind farm. At the same time, the method of placing high-voltage reactors in offshore substations will also increase the area of ​​offshore substations and increase the construction cost of offshore substations. Summary of the invention

[0004] In order to solve the defects of the above-mentioned prior art, the present invention provides an offshore wind power reactive power compensation configuration method and system to solve the problem that the traditional offshore wind power reactive power compensation method usually cannot balance the capacitive reactive power of the field area on site, which makes the line loss in the field area too large, the power frequency overvoltage is too high, affects the safe use of the equipment, and cannot fully reduce the network loss of the offshore wind farm. At the same time, the method of arranging high-voltage reactors in offshore substations will also increase the area of ​​offshore substations and increase the construction cost of offshore substations.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for configuring reactive power compensation for offshore wind power includes the following steps:

[0007] Step 1: construct a reactive power compensation configuration model for the offshore wind farm according to the line parameters of the offshore wind farm's collection line and the sending submarine cable, the equipment parameters of the wind turbine side box transformer of each wind turbine in the offshore wind farm, the equipment parameters of the main transformer of the offshore booster station of the offshore wind farm, and the power parameters of each wind turbine in the offshore wind farm, wherein the reactive power compensation configuration model includes a first module and a second module;

[0008] Step 2: The connection point between the offshore wind farm's collection line and each wind turbine, and the connection point between the offshore wind farm's sending submarine cable and the onshore centralized control center are taken as nodes; under full power conditions, the first module uses the active injection power value and the reactive injection power value of each of the nodes as input, and uses the reactive injection power value of each of the nodes as the first control variable, performs AC power flow calculation on the offshore wind farm, and outputs the network loss allocation coefficient corresponding to each of the nodes;

[0009] Step 3: Sort the nodes in descending order according to the corresponding network loss sharing coefficients, and set the top nodes as preset installation nodes;

[0010] Step 4: Under full-generation conditions, the reactive compensation capacity corresponding to each preset installation node is input into the second module, and the second module outputs the predicted value corresponding to the set network loss target parameter; the optimization goal is to minimize the predicted value corresponding to the set network loss target parameter, and the reactive compensation capacity of each preset installation node is used as the second control variable. The reactive compensation configuration model is solved in combination with the set constraints to obtain the optimal reactive compensation capacity corresponding to each preset installation node.

[0011] By taking the connection point between the collector line of the offshore wind farm and each wind turbine (in actual installation, the location where the reactive compensation equipment is installed at the node where the collector line of the offshore wind farm connects with the wind turbine usually refers to the wind turbine side box transformer of the wind turbine), and the connection point between the sending submarine cable of the offshore wind farm and the onshore centralized control center as nodes; and then calculating the network loss sharing coefficient of each node through the first module, the efficiency ranking of setting reactive compensation equipment at each node to reduce the network loss of the offshore wind farm can be obtained, and then each of the preset installation nodes can be obtained. Then, the second module is used to obtain the optimal reactive compensation capacity corresponding to each of the preset installation nodes; so that the offshore wind power reactive compensation configuration method provided by the present invention can quickly select key nodes from each node as the preset installation nodes by calculating the network loss sharing coefficient of each node, and calculate the optimal reactive compensation capacity corresponding to each of the preset installation nodes; it can balance the capacitive reactive power of the field on site, fully reduce the network loss of the offshore wind farm, and effectively avoid the situation where the power frequency overvoltage is too high and affects the safe use of the equipment.

[0012] And because the offshore wind power reactive compensation configuration method provided by the present invention is adopted, the selected preset installation node will only be at the connection point between the offshore wind farm's collection line and the wind turbine (inside the wind turbine side box transformer of the wind turbine) or the connection point between the offshore wind farm's sending submarine cable and the onshore control center (the incoming line side of the onshore control center); it will not occupy the area of ​​the offshore substation, which is conducive to the compact layout of the offshore substation and saves the area and investment cost of the offshore substation.

[0013] The configuration of reactive power compensation devices in box-type transformers has been widely used in onshore box-type transformer substations (for example, but not limited to: the document "Calculation of reactive power compensation capacity and circuit breaker sensitivity of box-type transformer substation" installs reactive power compensation devices on the low-voltage side busbar of the box-type transformer to directly reduce the reactive power loss on the busbar, and the document "Intelligent integrated power capacitors in box-type transformer substation" arranges intelligent integrated capacitors in the box-type transformer to increase the reactive power compensation capacity of the box-type transformer). The installation of reactors in the box-type transformer on the wind turbine side has little effect on the volume of the box-type transformer and the installation of the wind turbine. Therefore, it is feasible to configure reactive power compensation devices in offshore wind power box-type transformers or on wind turbine platforms.

[0014] Furthermore, the set network loss target parameter is the network loss power of the offshore wind farm.

[0015] Furthermore, the network loss power of the offshore wind farm is calculated using the following formula:

[0016]

[0017] Among them, P 1 is the network loss power of the offshore wind farm; P i is the active injected power of the node where the i-th wind turbine in the offshore wind farm is connected to the collector line; P s The active power output from the onshore centralized control center of the offshore wind farm; N w is the number of wind turbines in the offshore wind farm.

[0018] In another technical solution, the set network loss target parameter is the sum of the network loss cost of the offshore wind farm and the reactive power compensation equipment cost of the offshore wind farm.

[0019] Furthermore, the sum of the network loss cost of the offshore wind farm and the reactive power compensation equipment cost of the offshore wind farm is calculated using the following formula:

[0020]

[0021] Among them, P 1 is the network loss power of the offshore wind farm; P i is the active injected power of the node where the i-th wind turbine in the offshore wind farm is connected to the collector line; P sThe active power output from the onshore centralized control center of the offshore wind farm; N w is the number of wind turbines in the offshore wind farm; N d is the number of the preset installation nodes; C d is the reactive power compensation capacity value of the dth preset installation node; A is the network loss conversion cost; B is the unit capacity reactor cost.

[0022] Furthermore, the method of outputting the network loss allocation coefficient corresponding to each of the nodes includes:

[0023] Setting an initial reactive power injection value and an initial active power injection value of each node, using the initial reactive power injection value and the initial active power injection value of each node as inputs of the first module, and obtaining an initial network loss power value of the offshore wind farm through AC power flow calculation;

[0024] The first module calculates and obtains a first reactive injection power value of any of the nodes, where the first reactive injection power value is the sum of a preset reactive injection power value and an initial reactive injection power value of the node;

[0025] The first reactive injection power value and the initial active injection power value of the node, as well as the initial reactive injection power value and the initial active injection power value of other nodes are used as inputs of the first module, and the network loss power change value of the offshore wind farm relative to the initial network loss power value is obtained through AC power flow calculation. The first module outputs the network loss power change value as the network loss sharing coefficient corresponding to the node.

[0026] Furthermore, the constraints include active power balance constraints, reactive power balance constraints, voltage quality constraints and reactive power compensation device installation capacity constraints.

[0027] Furthermore, the active power balance constraint is:

[0028]

[0029] Among them, P g is the active injection power of the g-th node; U g is the voltage value of the gth node under full power condition; U j is the voltage value of the jth node under full power condition; N is the number of nodes in the offshore wind farm; G gj is the conductance between the gth node and the jth node; B gj is the susceptance between the gth node and the jth node; θ gj is the phase angle difference between the g-th node and the j-th node.

[0030] Furthermore, if the g-th node belongs to a preset installation node, the reactive power balance constraint is:

[0031]

[0032] If the g-th node does not belong to the preset installation node, the reactive power balance constraint is:

[0033]

[0034] Among them, Q g is the reactive injection power of the g-th node; Q′ g is the reactive power compensation capacity of the g-th node; U g is the voltage value of the gth node under full power condition; U j is the voltage value of the jth node under full power condition; N is the number of nodes in the offshore wind farm; G gj is the conductance between the gth node and the jth node; B gj is the susceptance between the gth node and the jth node; θ gj is the phase angle difference between the g-th node and the j-th node.

[0035] Furthermore, the voltage quality constraint is:

[0036]

[0037] Among them, U g is the voltage value of the gth node under full power condition, is the voltage lower limit of the g-th node under full power condition; is the voltage upper limit of the g-th node under full power condition.

[0038] Furthermore, the installation capacity of the reactive power compensation device is limited to:

[0039]

[0040] Among them, C d is the reactive power compensation capacity value of the dth preset installation node; is the lower limit of reactive power compensation capacity of the dth preset installation node; It is the upper limit value of reactive power compensation capacity of the dth preset installation node.

[0041] Furthermore, the reactive power compensation configuration model also includes a third module;

[0042] In step 3, several nodes ranked high are set as preset installation nodes, and the remaining nodes are set as candidate installation nodes;

[0043] The offshore wind power reactive power compensation configuration method further includes:

[0044] Step 5: Under the zero-generation condition, the third module uses the optimal reactive power compensation capacity corresponding to each preset installation node as input, performs AC power flow calculation on the offshore wind farm, and obtains the voltage of each candidate installation node under the zero-generation condition;

[0045] Step 6: The third module detects the voltage of each of the alternative installation nodes under the zero-generation condition. If the voltage of each of the alternative installation nodes under the zero-generation condition is within the standard voltage range, the third module outputs the reactive compensation configuration plan of the offshore wind farm according to the optimal reactive compensation capacity corresponding to each preset installation node input. Otherwise, the third module sets the alternative installation node whose voltage exceeds the standard voltage range under the zero-generation condition as the preset installation node, and returns to step 4.

[0046] By verifying the voltage of each alternative installation node in the compensated site under extreme working conditions (zero-generation working conditions), setting the alternative installation nodes whose voltage is not within the standard voltage range as preset installation nodes, recalculating the reactive compensation capacity of each preset installation node, repeating the above process until the voltage of all alternative installation nodes is within the standard voltage range, and then outputting the optimal reactive compensation capacity corresponding to each preset installation node as the reactive compensation configuration plan of the offshore wind farm; the voltage quality of each node in the offshore wind farm can be ensured to the greatest extent while ensuring the reduction of the network loss of the offshore wind farm.

[0047] According to the offshore wind power reactive compensation configuration method provided by the present invention, the present invention also provides an offshore wind power reactive compensation configuration system, including a reactive compensation configuration model of the offshore wind farm constructed according to the line parameters of the offshore wind farm's collection line and the sending submarine cable, the equipment parameters of the wind turbine side box transformer of each wind turbine in the offshore wind farm, the equipment parameters of the main transformer of the offshore substation of the offshore wind farm, and the power parameters of each wind turbine in the offshore wind farm, the reactive compensation configuration model includes a first module and a second module.

[0048] According to the offshore wind power reactive compensation configuration method provided by the present invention, the present invention also provides an offshore wind power reactive compensation configuration system, including a reactive compensation configuration model of the offshore wind farm constructed according to the line parameters of the offshore wind farm's collection line and the sending submarine cable, the equipment parameters of the wind turbine side box transformer of each wind turbine in the offshore wind farm, the equipment parameters of the main transformer of the offshore substation of the offshore wind farm, and the power parameters of each wind turbine in the offshore wind farm, the reactive compensation configuration model includes a first module, a second module and a third module. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0050] Figure 1 is a flow chart of the offshore wind power reactive power compensation configuration method in Example 1;

[0051] Figure 2 It is a structural topological diagram of an offshore wind farm after reactors are configured using the offshore wind power reactive power compensation configuration method in Example 1. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0053] Embodiment 1:

[0054] like Figure 1 As shown, this embodiment 1 provides a method for configuring reactive power compensation for offshore wind power, comprising the following steps:

[0055] Step 1: According to the line parameters of the offshore wind farm's collection line and the sending submarine cable, the equipment parameters of the wind turbine side box transformer of each wind turbine in the offshore wind farm, the equipment parameters of the main transformer of the offshore booster station of the offshore wind farm, and the power parameters of each wind turbine in the offshore wind farm, a reactive compensation configuration model of the offshore wind farm is constructed, and the reactive compensation configuration model includes a first module and a second module;

[0056] Step 2: The connection point between the offshore wind farm's collection line and each wind turbine, as well as the connection point between the offshore wind farm's sending submarine cable and the onshore centralized control center are taken as nodes; under full power conditions, the first module uses the active injection power value and reactive injection power value of each node as input, and uses the reactive injection power value of each node as the first control variable to calculate the AC power flow of the offshore wind farm, and output the network loss allocation coefficient corresponding to each node;

[0057] Step 3: Sort the nodes according to their corresponding network loss allocation coefficients from large to small, and set the top nodes as preset installation nodes;

[0058] Step 4: Under full-power conditions, the reactive compensation capacity corresponding to each preset installation node is input into the second module, and the second module outputs the predicted value corresponding to the set network loss target parameter; the optimization goal is to minimize the predicted value corresponding to the set network loss target parameter, and the reactive compensation capacity of each preset installation node is used as the second control variable. The reactive compensation configuration model is solved in combination with the set constraints to obtain the optimal reactive compensation capacity corresponding to each preset installation node.

[0059] By taking the connection point between the collector line of the offshore wind farm and each wind turbine (in actual installation, the location where the reactive compensation equipment is installed at the node where the collector line of the offshore wind farm connects with the wind turbine is usually inside the wind turbine side box transformer of the wind turbine), and the connection point between the sending submarine cable of the offshore wind farm and the onshore centralized control center as nodes; and then calculating the network loss sharing coefficient of each node through the first module, the efficiency ranking of setting reactive compensation equipment at each node to reduce the network loss of the offshore wind farm can be obtained, and then each preset installation node can be obtained. Then, the second module is used to obtain the optimal reactive compensation capacity corresponding to each preset installation node; so that the offshore wind power reactive compensation configuration method provided by the present invention can quickly select key nodes as preset installation nodes from each node by calculating the network loss sharing coefficient of each node, and calculate the optimal reactive compensation capacity corresponding to each preset installation node; it can balance the capacitive reactive power of the field on site, fully reduce the network loss of the offshore wind farm, and effectively avoid the situation where the power frequency overvoltage is too high and affects the safe use of the equipment.

[0060] And because the offshore wind power reactive compensation configuration method provided by the present invention is adopted, the selected preset installation node will only be at the connection point between the offshore wind farm's collection line and the wind turbine (inside the wind turbine side box transformer of the wind turbine) or the connection point between the offshore wind farm's sending submarine cable and the onshore control center (the incoming line side of the onshore control center); it will not occupy the area of ​​the offshore substation, which is conducive to the compact layout of the offshore substation and saves the area and investment cost of the offshore substation.

[0061] The configuration of reactive power compensation devices in box-type transformers has been widely used in onshore box-type transformer substations (for example, but not limited to: the document "Calculation of reactive power compensation capacity and circuit breaker sensitivity of box-type transformer substation" installs reactive power compensation devices on the low-voltage side busbar of the box-type transformer to directly reduce the reactive power loss on the busbar, and the document "Intelligent integrated power capacitors in box-type transformer substation" arranges intelligent integrated capacitors in the box-type transformer to increase the reactive power compensation capacity of the box-type transformer). The installation of reactors in the box-type transformer on the wind turbine side has little effect on the volume of the box-type transformer and the installation of the wind turbine. Therefore, it is feasible to configure reactive power compensation devices in offshore wind power box-type transformers or on wind turbine platforms.

[0062] In this embodiment 1, the set network loss target parameter is the network loss power of the offshore wind farm.

[0063] Specifically, the network loss power of the offshore wind farm is calculated using the following formula:

[0064]

[0065] Among them, P 1 is the network loss power of the offshore wind farm; P i is the active injected power of the node where the i-th wind turbine in the offshore wind farm is connected to the collector line; P s The active power output from the onshore centralized control center of the offshore wind farm; N w is the number of wind turbines in the offshore wind farm.

[0066] Specifically, in this embodiment 1, the method of outputting the network loss allocation coefficient corresponding to each node includes:

[0067] The initial reactive power injection value and the initial active power injection value of each node are set, and the initial reactive power injection value and the initial active power injection value of each node are used as inputs of the first module, and the initial network loss power value of the offshore wind farm is obtained through AC power flow calculation;

[0068] The first module calculates and obtains a first reactive injection power value of any node, where the first reactive injection power value is the sum of a preset reactive injection power value and an initial reactive injection power value of the node;

[0069] The first reactive injection power value and the initial active injection power value of the node, as well as the initial reactive injection power value and the initial active injection power value of other nodes are used as inputs of the first module, and the network loss power change value of the offshore wind farm relative to the initial network loss power value is obtained through AC power flow calculation. The first module outputs the network loss power change value as the network loss allocation coefficient corresponding to the node.

[0070] In one of the examples of this embodiment 1, an offshore wind farm has 90 wind turbines with a single installed capacity of 11MW. The booster station contains two 500kV main transformers, and the capacity of a single main transformer is 550MVA. Every five 11MW wind turbines in the wind farm are one collector line, which contains a total of 18 collector lines. The voltage level of the collector line is 66kV. It is planned to lay 123km of 66kV on-site collector cables, which are connected to the booster station through 18 collector lines; the voltage level of the outgoing submarine cable is 500kV.

[0071] Among them, the collector line includes five types of cables, and the line parameters of the collector line are shown in Table 1.

[0072] Table 1 Line parameters of collector line

[0073]

[0074] Among them, the line parameters of the submarine cable are shown in Table 2.

[0075] Table 2 Line parameters of the submarine cable

[0076]

[0077] Among them, the equipment parameters of the main transformer of the offshore booster station of the offshore wind farm are shown in Table 3.

[0078] Table 3 Equipment parameters of the main transformer of the offshore booster station of the offshore wind farm

[0079] Number of main transformers Main transformer capacity MVA Main transformer voltage kV Main transformer short circuit impedance 2 2×550 500 / 66 14％

[0080] Among them, the equipment parameters of the wind turbine side box transformer of each wind turbine in the offshore wind farm are shown in Table 4.

[0081] Table 4 Equipment parameters of wind turbine side box transformers for each wind turbine in offshore wind farms

[0082] Number of box transformers Transformer capacity Transformer voltage kV Box transformer short circuit impedance 90 90×12.1MVA 66 / 0.69 7％

[0083] Based on the above example, the method of outputting the network loss allocation coefficient corresponding to each node is described in detail below:

[0084] The reactive power compensation configuration model of the offshore wind farm is used to simulate the full-power condition of the offshore wind farm. The runpf function of matpower is used to calculate the AC power flow of the simulated offshore wind farm, and the initial network loss power value of the offshore wind farm under the full-power condition is obtained.

[0085] Increase the reactive injection power of node 1 by 10 MVar, keep the other nodes unchanged, and use the runpf function to calculate the AC power flow again, obtain the difference between the network loss power value corresponding to the offshore wind farm in this state and the initial network loss power value, and use the difference as the network loss allocation coefficient of node 1; repeat the above steps from node 2 to node 91 to obtain the network loss allocation coefficient of all nodes. The network loss allocation coefficients of each node are shown in Table 5. The network loss allocation coefficients are arranged from top to bottom, and the first 19 nodes are taken as the preset installation nodes.

[0086] Table 5 Network loss allocation coefficient table for each node

[0087]

[0088]

[0089] like Figure 2As shown in Table 5, the node 91 at the connection between the outgoing submarine cable of the offshore wind farm and the onshore centralized control center is the node with the largest network loss sharing coefficient. The node 91 and the node at the connection between the wind turbine closest to the offshore booster station and the collector line on each collector line are also the top 19 nodes.

[0090] Therefore, in this embodiment 1, the preset installation nodes, i.e., the node 91 at the connection between the sending submarine cable and the onshore centralized control center, and the node at the connection between the wind turbine closest to the offshore booster station and the collection line on each collection line, total 19 nodes.

[0091] A land-based centralized control center reactor is installed at node 91 at the connection between the outgoing submarine cable and the land-based centralized control center, and transformer-side reactors are installed at a total of 18 nodes at the connection between the wind turbine closest to the offshore substation on each collection line and the collection line (specifically, inside the wind turbine-side transformer of the wind turbine).

[0092] Specifically, in this embodiment 1, the constraint conditions include active power balance constraint, reactive power balance constraint, voltage quality constraint and reactive power compensation device installation capacity constraint.

[0093] Specifically, in this embodiment 1, the active power balance constraint is:

[0094]

[0095] Among them, P g is the active injection power of the g-th node; U g is the voltage value of the gth node under full power condition; U j is the voltage value of the jth node under full power condition; N is the number of nodes in the offshore wind farm; G gj is the conductance between the gth node and the jth node; B gj is the susceptance between the gth node and the jth node; θ gj is the phase angle difference between the g-th node and the j-th node.

[0096] Specifically, in this embodiment 1, if the g-th node belongs to a preset installation node, the reactive power balance constraint is:

[0097]

[0098] If the gth node does not belong to the preset installation node, the reactive power balance constraint is:

[0099]

[0100] Among them, Q g is the reactive injection power of the g-th node; Q′ g is the reactive power compensation capacity of the g-th node; Ug is the voltage value of the gth node under full power condition; U j is the voltage value of the jth node under full power condition; N is the number of nodes in the offshore wind farm; G gj is the conductance between the gth node and the jth node; B gj is the susceptance between the gth node and the jth node; θ gj is the phase angle difference between the g-th node and the j-th node.

[0101] Specifically, in this embodiment 1, the voltage quality constraint is:

[0102]

[0103] Among them, U g is the voltage value of the gth node under full power condition, is the voltage lower limit of the g-th node under full power condition; is the voltage upper limit of the g-th node under full power condition.

[0104] Specifically, in this embodiment 1, the installation capacity of the reactive power compensation device is limited to:

[0105]

[0106] Among them, C d is the reactive power compensation capacity value of the dth preset installation node; is the lower limit of reactive power compensation capacity of the dth preset installation node; It is the upper limit value of reactive power compensation capacity of the dth preset installation node.

[0107] Specifically, in this embodiment 1, the reactive power compensation configuration model further includes a third module;

[0108] In step 3, several nodes ranked high are set as preset installation nodes, and the remaining nodes are set as candidate installation nodes;

[0109] Offshore wind power reactive power compensation configuration methods also include:

[0110] Step 5: Under zero-generation conditions, the third module uses the optimal reactive power compensation capacity corresponding to each preset installation node as input, calculates the AC power flow of the offshore wind farm, and obtains the voltage of each candidate installation node under zero-generation conditions;

[0111] Step 6: The third module detects the voltage of each alternative installation node under the zero-generation condition. If the voltage of each alternative installation node under the zero-generation condition is within the standard voltage range, the third module outputs the reactive power compensation configuration plan of the offshore wind farm according to the optimal reactive power compensation capacity corresponding to each preset installation node input. Otherwise, the third module sets the alternative installation node whose voltage exceeds the standard voltage range under the zero-generation condition as the preset installation node, and returns to step 4.

[0112] By verifying the voltage of each alternative installation node in the compensated site under extreme working conditions (zero-generation working conditions), setting the alternative installation nodes whose voltage is not within the standard voltage range as preset installation nodes, recalculating the reactive compensation capacity of each preset installation node, repeating the above process until the voltage of all alternative installation nodes is within the standard voltage range, and then outputting the optimal reactive compensation capacity corresponding to each preset installation node as the reactive compensation configuration plan of the offshore wind farm; the voltage quality of each node in the offshore wind farm can be ensured to the greatest extent while ensuring the reduction of the network loss of the offshore wind farm.

[0113] Embodiment 2:

[0114] This embodiment 2 provides an offshore wind power reactive power compensation configuration method. The offshore wind power reactive power compensation configuration method provided by embodiment 2 is basically the same as the offshore wind power reactive power compensation configuration method provided by embodiment 1, except that different network loss target parameters are set.

[0115] In this embodiment 2, the network loss target parameter is set to be the sum of the network loss cost of the offshore wind farm and the reactive power compensation equipment cost of the offshore wind farm.

[0116] Specifically, in this embodiment 2, the sum of the network loss cost of the offshore wind farm and the reactive power compensation equipment cost of the offshore wind farm is calculated using the following formula:

[0117]

[0118] Among them, P 1 is the network loss power of the offshore wind farm; P i is the active injected power of the node where the i-th wind turbine in the offshore wind farm is connected to the collector line; P s The active power output from the onshore centralized control center of the offshore wind farm; N w is the number of wind turbines in the offshore wind farm; N d is the number of preset installation nodes; C d is the reactive power compensation capacity value of the dth preset installation node; A is the network loss conversion cost; B is the unit capacity reactor cost.

[0119] Embodiment 3:

[0120] According to the offshore wind power reactive compensation configuration method provided in Example 1, Example 3 provides an offshore wind power reactive compensation configuration system, including a reactive compensation configuration model of the offshore wind farm constructed according to the line parameters of the offshore wind farm's collection line and the sending submarine cable, the equipment parameters of the wind turbine side box transformer of each wind turbine in the offshore wind farm, the equipment parameters of the main transformer of the offshore substation of the offshore wind farm, and the power parameters of each wind turbine in the offshore wind farm, the reactive compensation configuration model includes a first module and a second module.

[0121] Embodiment 4:

[0122] According to the offshore wind power reactive compensation configuration method provided in Example 1, Example 4 provides an offshore wind power reactive compensation configuration system, including a reactive compensation configuration model of the offshore wind farm constructed according to the line parameters of the offshore wind farm's collection line and the sending submarine cable, the equipment parameters of the wind turbine side box transformer of each wind turbine in the offshore wind farm, the equipment parameters of the main transformer of the offshore substation of the offshore wind farm, and the power parameters of each wind turbine in the offshore wind farm, the reactive compensation configuration model includes a first module, a second module and a third module.

[0123] The offshore wind power reactive power compensation configuration method and system provided by the present invention have at least the following technical effects or advantages:

[0124] 1. By taking the connection point between the collector line of the offshore wind farm and each wind turbine (in actual installation, the location where the reactive compensation equipment is installed at the node where the collector line of the offshore wind farm connects with the wind turbine is usually inside the wind turbine side box transformer of the wind turbine), and the connection point between the sending submarine cable of the offshore wind farm and the onshore centralized control center as a node; and then calculating the network loss sharing coefficient of each node through the first module, the efficiency ranking of setting reactive compensation equipment at each node to reduce the network loss of the offshore wind farm can be obtained, and then each preset installation node can be obtained. Then, the second module is used to obtain the optimal reactive compensation capacity corresponding to each preset installation node; so that the offshore wind power reactive compensation configuration method provided by the present invention can quickly select key nodes as preset installation nodes from each node by calculating the network loss sharing coefficient of each node, and calculate the optimal reactive compensation capacity corresponding to each preset installation node; it can balance the capacitive reactive power of the field on the spot, fully reduce the network loss of the offshore wind farm, and effectively avoid the situation where the power frequency overvoltage is too high and affects the safe use of the equipment.

[0125] 2. Due to the adoption of the offshore wind power reactive compensation configuration method provided by the present invention, the selected preset installation node will only be at the connection point between the offshore wind farm's collection line and the wind turbine (inside the wind turbine side box transformer of the wind turbine) or the connection point between the offshore wind farm's sending submarine cable and the onshore control center (the incoming line side of the onshore control center); it will not occupy the area of ​​the offshore substation, which is conducive to the compact layout of the offshore substation and saves the area and investment cost of the offshore substation.

[0126] 3. By verifying the voltage of each alternative installation node in the compensated site under extreme working conditions (zero-generation working conditions), and then setting the alternative installation nodes whose voltage is not within the standard voltage range as preset installation nodes, recalculating the reactive compensation capacity of each preset installation node, repeating the above process until the voltage of all alternative installation nodes is within the standard voltage range, and then outputting the optimal reactive compensation capacity corresponding to each preset installation node as the reactive compensation configuration plan of the offshore wind farm; this can ensure the reduction of the network loss of the offshore wind farm while ensuring the voltage quality of each node of the offshore wind farm to the greatest extent.

[0127] The above are only specific application examples of the present invention and do not constitute any limitation to the protection scope of the present invention. Any technical solutions formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the present invention.

Claims

1. A method for configuring reactive power compensation for offshore wind power, characterized in that: The following steps are involved: Step 1: construct a reactive power compensation configuration model for the offshore wind farm according to the line parameters of the offshore wind farm's collection line and the sending submarine cable, the equipment parameters of the wind turbine side box transformer of each wind turbine in the offshore wind farm, the equipment parameters of the main transformer of the offshore booster station of the offshore wind farm, and the power parameters of each wind turbine in the offshore wind farm, wherein the reactive power compensation configuration model includes a first module and a second module; Step 2: The connection point between the offshore wind farm’s collection line and each wind turbine, as well as the connection point between the offshore wind farm’s outgoing submarine cable and the onshore centralized control center are taken as nodes; Under full power condition, the first module uses the active injection power value and reactive injection power value of each node as input, and uses the reactive injection power value of each node as the first control variable, performs AC power flow calculation on the offshore wind farm, and outputs the network loss allocation coefficient corresponding to each node; Step 3: Sort the nodes in descending order according to the corresponding network loss sharing coefficients, and set the top nodes as preset installation nodes; Step 4: Under full power conditions, the reactive power compensation capacity corresponding to each preset installation node is input into the second module, and the second module outputs the predicted value corresponding to the set network loss target parameter; The optimization goal is to minimize the predicted value corresponding to the set network loss target parameter, the reactive compensation capacity of each preset installation node is used as the second control variable, and the reactive compensation configuration model is solved in combination with the set constraints to obtain the optimal reactive compensation capacity corresponding to each preset installation node.

2. The offshore wind power reactive power compensation configuration method according to claim 1, characterized in that: The set network loss target parameter is the network loss power of the offshore wind farm.

3. The offshore wind power reactive power compensation configuration method according to claim 2, characterized in that: The network loss power of offshore wind farms is calculated using the following formula: Where P1 is the network loss power of the offshore wind farm; P i is the active injected power of the node where the i-th wind turbine in the offshore wind farm is connected to the collector line; P s The active power output from the onshore centralized control center of the offshore wind farm; N w is the number of wind turbines in the offshore wind farm.

4. The offshore wind power reactive power compensation configuration method according to claim 1, characterized in that: The set network loss target parameter is the sum of the network loss cost of the offshore wind farm and the reactive power compensation equipment cost of the offshore wind farm.

5. The offshore wind power reactive power compensation configuration method according to claim 1, characterized in that: The method of outputting the network loss allocation coefficient corresponding to each of the nodes includes: Setting an initial reactive power injection value and an initial active power injection value of each node, using the initial reactive power injection value and the initial active power injection value of each node as inputs of the first module, and obtaining an initial network loss power value of the offshore wind farm through AC power flow calculation; The first module calculates and obtains a first reactive injection power value of any of the nodes, where the first reactive injection power value is the sum of a preset reactive injection power value and an initial reactive injection power value of the node; The first reactive injection power value and the initial active injection power value of the node, as well as the initial reactive injection power value and the initial active injection power value of other nodes are used as inputs of the first module, and the network loss power change value of the offshore wind farm relative to the initial network loss power value is obtained through AC power flow calculation. The first module outputs the network loss power change value as the network loss sharing coefficient corresponding to the node.

6. The offshore wind power reactive power compensation configuration method according to claim 1, characterized in that: The constraints include active power balance constraints, reactive power balance constraints, voltage quality constraints and reactive power compensation device installation capacity constraints.

7. The offshore wind power reactive power compensation configuration method according to claim 6, characterized in that: The active power balance constraint is: Among them, P g is the active injection power of the g-th node; U g is the voltage value of the gth node under full power condition; U j is the voltage value of the jth node under full power condition; N is the number of nodes in the offshore wind farm; G gj is the conductance between the gth node and the jth node; B gj is the susceptance between the gth node and the jth node; θ gj is the phase angle difference between the g-th node and the j-th node.

8. The offshore wind power reactive power compensation configuration method according to claim 6, characterized in that: If the g-th node belongs to the preset installation node, the reactive power balance constraint is: If the g-th node does not belong to the preset installation node, the reactive power balance constraint is: Among them, Q g is the reactive injection power of the g-th node; Q′ g is the reactive power compensation capacity of the g-th node; U g is the voltage value of the gth node under full power condition; U j is the voltage value of the jth node under full power condition; N is the number of nodes in the offshore wind farm; G gj is the conductance between the gth node and the jth node; B gj is the susceptance between the gth node and the jth node; θ gj is the phase angle difference between the g-th node and the j-th node.

9. The offshore wind power reactive power compensation configuration method according to claim 6, characterized in that: The voltage quality constraint is: Among them, U g is the voltage value of the gth node under full-power condition, is the voltage lower limit of the g-th node under full power condition; is the voltage upper limit of the g-th node under full power condition.

10. The offshore wind power reactive power compensation configuration method according to claim 6, characterized in that: The installation capacity limit of the reactive power compensation device is: Among them, C d is the reactive power compensation capacity value of the dth preset installation node; is the lower limit of reactive power compensation capacity of the dth preset installation node; It is the upper limit value of reactive power compensation capacity of the dth preset installation node.

11. The offshore wind power reactive power compensation configuration method according to claim 1, characterized in that: The reactive power compensation configuration model also includes a third module; In step 3, several nodes ranked high are set as preset installation nodes, and the remaining nodes are set as candidate installation nodes; The offshore wind power reactive power compensation configuration method further includes: Step 5: Under the zero-generation condition, the third module uses the optimal reactive power compensation capacity corresponding to each preset installation node as input, performs AC power flow calculation on the offshore wind farm, and obtains the voltage of each candidate installation node under the zero-generation condition; Step 6: The third module detects the voltage of each of the alternative installation nodes under the zero-generation condition. If the voltage of each of the alternative installation nodes under the zero-generation condition is within the standard voltage range, the third module outputs the reactive compensation configuration plan of the offshore wind farm according to the optimal reactive compensation capacity corresponding to each preset installation node input. Otherwise, the third module sets the alternative installation node whose voltage exceeds the standard voltage range under the zero-generation condition as the preset installation node, and returns to step 4.

12. An offshore wind power reactive power compensation configuration system, characterized in that: The reactive power compensation configuration model of the offshore wind farm is constructed according to the line parameters of the collection line and the sending submarine cable of the offshore wind farm, the equipment parameters of the wind turbine side box transformer of each wind turbine of the offshore wind farm, the equipment parameters of the main transformer of the offshore booster station of the offshore wind farm, and the power parameters of each wind turbine of the offshore wind farm, wherein the reactive power compensation configuration model includes a first module and a second module; The offshore wind power reactive power compensation configuration system is used to execute the steps in the offshore wind power reactive power compensation configuration method as described in any one of claims 1-10.

13. An offshore wind power reactive power compensation configuration system, characterized in that: The reactive power compensation configuration model of the offshore wind farm is constructed according to the line parameters of the collection line and the sending submarine cable of the offshore wind farm, the equipment parameters of the wind turbine side box transformer of each wind turbine of the offshore wind farm, the equipment parameters of the main transformer of the offshore booster station of the offshore wind farm, and the power parameters of each wind turbine of the offshore wind farm, wherein the reactive power compensation configuration model includes a first module, a second module and a third module; The offshore wind power reactive power compensation configuration system is used to execute the steps in the offshore wind power reactive power compensation configuration method as described in any one of claims 1-11.

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