A far-sea wind power multi-terminal heterogeneous power collection system reactive power collaborative optimization method and device, a terminal device and a storage medium

Abstract

The application discloses a kind of far-sea wind power multi-terminal heterogeneous power collection system reactive power collaborative optimization method, device, terminal equipment and storage medium, belong to reactive power optimization technical field, the above-mentioned method is: obtaining the bus data of far-sea wind power collection system, branch data, generator data and the bus data of several candidate input combinations of alternating current filter, reactive power optimization solution is carried out to each candidate input combination, obtain the candidate input combination corresponding to minimum objective function value and optimal reactive power optimization parameter, and carry out reactive power optimization adjustment;When reactive power optimization solution is carried out, the coefficient matrix of alternating current flow linear equation set is constructed based on admittance matrix, the right end vector is constructed based on fan active power, current fan reactive power and current grid-connected point voltage amplitude, and the approximate voltage phasor of non-grid-connected point is obtained after equation set is solved, and then the optimal reactive power optimization parameter and objective function value are determined. By implementing the present application, the problems of large calculation overhead and low calculation efficiency in the prior art can be solved.

Description

Technical Field

[0001] This invention relates to the field of reactive power optimization technology, and in particular to a method, apparatus, terminal equipment and storage medium for reactive power collaborative optimization of multi-terminal heterogeneous power collection systems in offshore wind power. Background Technology

[0002] As offshore wind power develops towards deeper waters and larger-scale operations, high-voltage direct current (HVDC) transmission has become the main technology for transmitting offshore wind power. To balance the requirements of compact and lightweight offshore converter platforms with system operational reliability, multi-terminal heterogeneous HVDC transmission systems based on a hybrid network of diode rectifier units (DRUs) and modular multilevel converters (MMCs) have attracted widespread attention. In this system, the DRU, as the main sending-end converter, undertakes the rectification and transmission of most of the active power, but it lacks reactive power regulation capabilities. The large amount of reactive power required during the commutation process must be provided collaboratively by various reactive power compensation devices on the AC collector system side, including wind turbines, auxiliary MMCs, and AC filters.

[0003] Existing reactive power co-optimization methods typically employ complete nonlinear AC power flow constraints to construct a power flow model for the power collection system. For a multi-megawatt offshore wind power collection system containing hundreds of nodes, the nonlinear power flow constraints cause the optimization problem to exhibit highly non-convex characteristics. Therefore, in the optimization solution process, each calculation of the objective function and constraint conditions requires a nonlinear power flow iteration calculation, resulting in huge computational overhead and low computational efficiency. Summary of the Invention

[0004] This invention provides a method, device, terminal equipment, and storage medium for reactive power collaborative optimization of multi-terminal heterogeneous power collection systems in offshore wind power. It can solve the problems of huge computational overhead and low computational efficiency in existing technologies that use complete nonlinear AC power flow constraints to construct a power flow model of the power collection system to achieve reactive power optimization.

[0005] An embodiment of the present invention provides a reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power, comprising: Obtain bus data, branch data, generator data, and several candidate combinations of AC filters for offshore wind power collection systems, and construct an admittance matrix based on the bus data and branch data. For each candidate input combination, based on the current candidate input combination, generator data, and admittance matrix, the reactive power optimization solution operation is repeatedly executed to obtain the corresponding optimal reactive power optimization parameters and objective function value. Then, reactive power optimization adjustment is performed based on the candidate input combination and optimal reactive power optimization parameters corresponding to the minimum objective function value. The reactive power optimization solution operation includes: Obtain the current reactive power output of the wind turbine and the current voltage amplitude at the grid connection point; wherein, the initial reactive power output of the wind turbine is calculated based on the preset initial power factor, and the initial voltage amplitude at the grid connection point is calculated based on the preset grid connection point boundary voltage; Construct the coefficient matrix of the current AC power flow linear equation system based on the admittance matrix. Construct the right-hand vector of the current AC power flow linear equation system based on the active power output of the wind turbine, the current reactive power output of the wind turbine and the current voltage amplitude of the grid connection point in the generator data. Perform matrix solution on the current AC power flow linear equation system to obtain the current approximate voltage phasor of the non-grid connection point. Based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current voltage amplitude at the grid connection point, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state. If the current solution convergence state is convergence, the current reactive power optimization parameters and the current objective function value are used as the optimal reactive power optimization parameters and objective function value corresponding to the current candidate input combination; otherwise, based on the current objective function value and the current constraint violation, the updated wind turbine reactive power output and grid connection point voltage amplitude are calculated.

[0006] Furthermore, based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current grid connection point voltage amplitude, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor, the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state are calculated and determined, including: Obtain the reactive power penalty weights of the auxiliary MMC and the reactive power penalty weights of the wind turbine. Based on the preset rated reactive power capacity of the auxiliary MMC, the reactive power penalty weight of the auxiliary MMC, and the reactive power penalty weight of the wind turbine, the objective function of the multi-source reactive power collaborative optimization model is constructed with the goal of minimizing the grid loss of the power collection system and maximizing the dynamic reactive power margin of the auxiliary MMC. Based on the preset node voltage amplitude limit, the preset rated reactive power capacity of the auxiliary MMC, the preset branch apparent power rated capacity, and the preset wind turbine reactive power output limit, the constraints of the multi-source reactive power collaborative optimization model are constructed. Based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, current objective function value, and current constraint violation amount. Based on the current reactive power optimization parameters, the current objective function value, and the current constraint violation, the change magnitude of the current optimization parameters and the change magnitude of the current objective function are calculated. If the magnitude of the change in the current optimization parameters, the magnitude of the change in the current objective function, and the current constraint violation all do not exceed the corresponding preset thresholds, then the current solution convergence state is converged; otherwise, the current solution convergence state is non-converged.

[0007] Furthermore, based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor, the current reactive power optimization parameters, current objective function value, and current constraint violation are calculated and determined, including: Based on the current approximate voltage phasor, admittance matrix, and current candidate input combinations, the current node precise re-injection power, current total active power loss, current branch apparent power, and current grid connection point original boundary power are calculated. The original boundary power of the current grid connection point is corrected based on the active power output of the wind turbine, the current reactive power output of the wind turbine, and the current node precise re-injection power, to obtain the corrected current grid connection point boundary power and the current grid connection point active power sent into the DRU. Based on the current active power and voltage amplitude of the DRU at the current grid connection point, the current DC voltage margin and reactive power demand at the current DRU grid connection point are calculated. Based on the current reactive power demand of the DRU grid connection point, the corrected current grid connection point boundary power, and the current candidate input combination, the reactive power required by the current auxiliary MMC is calculated. Based on the reactive power required by the current auxiliary MMC, the current candidate input combination, the current total active power loss, the current reactive power of the wind turbine, the voltage amplitude of the non-grid-connected point in the bus data, the voltage amplitude of the current grid-connected point, the current apparent power of the branch, the current DC voltage margin, the objective function and the constraints, the current objective function value and the current constraint violation amount are calculated. The current reactive power output of the wind turbine, the current voltage amplitude at the grid connection point, and the reactive power output required by the current auxiliary MMC are used as the current reactive power optimization parameters.

[0008] Furthermore, based on the current approximate voltage phasor, admittance matrix, and current candidate input combinations, the current node's precise re-injection power, current total active power loss, current branch apparent power, and current grid connection point's original boundary power are calculated, including: The precise complex injection power of the current node is calculated based on the current approximate voltage phasor and the preset precise node power equation constructed based on the admittance matrix. Based on the current approximate voltage phasor and admittance matrix, the complex power at the beginning of the current branch and the complex power at the end of the current branch are calculated. Take the real part of the sum of the complex power at the beginning of the current branch and the complex power at the end of the current branch to obtain the active power loss of the current branch; Based on the non-negative sum of the current active power network losses of all branches, the current total active power network loss is obtained; The apparent power of the current branch is calculated based on the complex power at the beginning and end of the current branch. The precise re-injection power of the current grid connection point is extracted from the precise re-injection power of the current node. The real part of the precisely re-injected power at the current grid connection point is taken as the original boundary active power of the current grid connection point, and the imaginary part of the precisely re-injected power at the current grid connection point is taken as the original boundary reactive power of the current grid connection point, and then the original boundary power of the current grid connection point is obtained.

[0009] Furthermore, based on the active power output of the wind turbine, the current reactive power output of the wind turbine, and the current node's precise re-injection power corresponding to the original boundary power of the current grid connection point, corrections are made to obtain the corrected current grid connection point boundary power and the current grid connection point active power fed into the DRU, including: Based on the current node's precise re-injection power, the active power output of the wind turbine, and the current reactive power output of the wind turbine, the precise injection active power deviation and the precise injection reactive power deviation of the current non-grid-connected point are calculated. The precise injection active power deviation and precise injection reactive power deviation of all current non-grid-connected points are summed to obtain the current total network active power deviation and the current total network reactive power deviation. The current active power deviation of the entire network is superimposed on the original boundary active power of the current grid connection point to obtain the corrected boundary active power of the current grid connection point; The current reactive power deviation of the entire network is superimposed on the original boundary reactive power of the current grid connection point to obtain the corrected boundary reactive power of the current grid connection point; Based on the corrected active power and reactive power at the current grid connection point boundary, the corrected current grid connection point boundary power is obtained. Take the negative of the corrected current grid connection point boundary active power to obtain the current grid connection point active power fed into the DRU.

[0010] Furthermore, based on the current active power and voltage amplitude at the grid connection point fed into the DRU, the current DC voltage margin and reactive power demand at the current DRU grid connection point are calculated, including: Obtain the current valve-side AC line voltage and commutation reactance; Using the current grid-connected active power and current grid-connected voltage amplitude fed into the DRU as inputs, and DC current as an unknown variable, a steady-state interface model of the DRU converter is constructed. The steady-state interface model of the DRU converter is solved to obtain the current DC current; The current DC voltage margin is calculated based on the current DC current, the current AC line voltage on the valve side, and the commutation reactance. Based on the corrected active power at the current grid connection point boundary, the three-phase complex power at the current grid connection point is calculated. Take the imaginary part of the three-phase complex power at the current grid connection point to obtain the reactive power demand at the current DRU grid connection point.

[0011] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments; This invention provides a reactive power collaborative optimization device for a multi-terminal heterogeneous power collection system in offshore wind power, comprising: Data acquisition module and reactive power optimization and adjustment module; The data acquisition module is used to acquire bus data, branch data, generator data, and several candidate input combinations of AC filters for offshore wind power collection systems, and to construct an admittance matrix based on the bus data and branch data. The reactive power optimization and adjustment module is used to repeatedly perform reactive power optimization solution operations for each candidate input combination based on the current candidate input combination, generator data and admittance matrix to obtain the corresponding optimal reactive power optimization parameters and objective function value, and to perform reactive power optimization adjustment based on the candidate input combination and optimal reactive power optimization parameters corresponding to the minimum objective function value. The reactive power optimization solution operation includes: Obtain the current reactive power output of the wind turbine and the current voltage amplitude at the grid connection point; wherein, the initial reactive power output of the wind turbine is calculated based on the preset initial power factor, and the initial voltage amplitude at the grid connection point is calculated based on the preset grid connection point boundary voltage; Construct the coefficient matrix of the current AC power flow linear equation system based on the admittance matrix. Construct the right-hand vector of the current AC power flow linear equation system based on the active power output of the wind turbine, the current reactive power output of the wind turbine and the current voltage amplitude of the grid connection point in the generator data. Perform matrix solution on the current AC power flow linear equation system to obtain the current approximate voltage phasor of the non-grid connection point. Based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current voltage amplitude at the grid connection point, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state. If the current solution convergence state is convergence, the current reactive power optimization parameters and the current objective function value are used as the optimal reactive power optimization parameters and objective function value corresponding to the current candidate input combination; otherwise, based on the current objective function value and the current constraint violation, the updated wind turbine reactive power output and grid connection point voltage amplitude are calculated.

[0012] Furthermore, the reactive power optimization and adjustment module includes: The system includes a weight acquisition unit, an objective function construction unit, a constraint construction unit, a data calculation unit, an amplitude calculation unit, and a convergence judgment unit. The weight acquisition unit is used to acquire the reactive power penalty weight of the auxiliary MMC and the reactive power penalty weight of the wind turbine. The objective function construction unit is used to construct the objective function of a multi-source reactive power collaborative optimization model with the objectives of minimizing grid loss of the power collection system and maximizing the dynamic reactive power margin of the auxiliary MMC, based on the preset rated reactive power capacity of the auxiliary MMC, the reactive power penalty weight of the auxiliary MMC and the reactive power penalty weight of the wind turbine. The constraint construction unit is used to construct the constraint conditions of the multi-source reactive power collaborative optimization model based on the preset node voltage amplitude limit, the preset rated reactive power capacity of the auxiliary MMC, the preset branch apparent power rated capacity, and the preset wind turbine reactive power output limit. The data calculation unit is used to calculate and determine the current reactive power optimization parameters, the current objective function value, and the current constraint violation amount based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor. The amplitude calculation unit is used to calculate the amplitude value of the change in the current optimization parameters and the amplitude value of the change in the current objective function based on the current reactive power optimization parameters, the current objective function value and the current constraint violation amount; The convergence judgment unit is used to determine if the current solution convergence state is converged if the change magnitude of the current optimization parameter, the change magnitude of the current objective function, and the current constraint violation do not exceed the corresponding preset threshold; otherwise, the current solution convergence state is non-convergent.

[0013] Based on the above method embodiments, the present invention provides a corresponding terminal device embodiment; The present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the reactive power collaborative optimization method of a multi-terminal heterogeneous power collection system for offshore wind power described in any embodiment of the present invention.

[0014] Based on the above method embodiments, the present invention provides a corresponding storage medium embodiment; The present invention provides a storage medium including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the reactive power collaborative optimization method of a multi-terminal heterogeneous power collection system for offshore wind power described in any embodiment of the present invention.

[0015] The embodiments of the present invention have the following beneficial effects: This invention provides a method, apparatus, terminal equipment, and storage medium for reactive power coordinated optimization of a multi-terminal heterogeneous power collection system for offshore wind power. The method acquires basic data such as bus data, branch data, generator data, and several candidate input combinations of AC filters from the offshore wind power collection system. Based on the bus data and branch data, an admittance matrix is ​​constructed. Then, for each candidate input combination, the reactive power optimization solution operation is repeatedly performed based on the current candidate input combination, generator data, and admittance matrix to obtain the corresponding optimal reactive power optimization parameters and objective function value. Based on the candidate input combination corresponding to the minimum objective function value and the optimal reactive power optimization parameters, reactive power optimization adjustment is performed to achieve reactive power optimization adjustment of the offshore wind power collection system. In the repeated execution of reactive power optimization solution operations, the current reactive power output of the wind turbine and the current voltage amplitude at the grid connection point are first obtained. Based on the admittance matrix, the coefficient matrix of the current AC power flow linear equation system is constructed. Based on the active power output of the wind turbine, the current reactive power output of the wind turbine, and the current voltage amplitude at the grid connection point from the generator data, the right-hand vector of the current AC power flow linear equation system is constructed. The current AC power flow linear equation system is then solved by matrix operation to obtain the current approximate voltage phasor at the non-grid connection point. Finally, based on the current approximate voltage phasor, the optimal reactive power optimization parameters and objective function value corresponding to the current candidate input combination are determined. This invention eliminates the need for nonlinear power flow iteration in each calculation of existing technologies, instead transforming the nonlinear power flow calculation into a linear equation system form. The approximate voltage phasor can be obtained through a single matrix solution, eliminating the need for power flow iteration loops throughout the process. Furthermore, this invention replaces the nonlinear power flow constraints in existing technologies with a linearized power flow model of AC power flow linear equation system. Based on this linear mapping relationship, the non-convexity of the optimization problem is weakened, significantly reducing the computational load of calculating the objective function and reactive power optimization parameters in a single step, thus reducing computational overhead. Attached Figure Description

[0016] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating a reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power, provided by an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram comparing the active power output of a current collection system according to an embodiment of the present invention.

[0019] Figure 3This is a schematic diagram comparing the reactive power demand on the DRU converter side according to an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram comparing the net reactive power at the grid connection point according to an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram of the reactive power collaborative optimization device for a multi-terminal heterogeneous power collection system for offshore wind power, provided in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0024] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0025] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0026] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0027] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0028] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0029] See Figure 1 To address the problem that existing technologies employ complete nonlinear AC power flow constraints to construct power flow models for reactive power optimization, resulting in significant computational overhead and low efficiency, this invention provides a method for collaborative reactive power optimization in multi-terminal heterogeneous power collection systems for offshore wind power, comprising: Step S1: Obtain bus data, branch data, generator data, and several candidate input combinations of AC filters for the offshore wind power collection system, and construct the admittance matrix based on the bus data and branch data; Specifically, the offshore wind power collection system is a multi-terminal heterogeneous collection system. The bus data includes: bus number and rated voltage; the branch data includes: the starting bus number, ending bus number, resistance, reactance, ground charge susceptance, and rated capacity; the generator data includes: the grid-connected bus number, active power output, and upper and lower limits of reactive power output of each wind turbine (i.e., wind turbine); the candidate input combination refers to traversing all feasible filter input state combinations using an enumeration method. Illustratively, for a filter, its input state is divided into "input" and "disconnected." Therefore, assuming the system has 5 filter groups, "inputting groups 1, 2, and 3, and disconnecting groups 4 and 5" is an input combination. If this combination is feasible, it is considered a candidate input combination.

[0030] Specifically, the impedance parameters of each component in the above data are uniformly converted into per-unit values, and a bus admittance matrix and a branch admittance matrix are constructed as the admittance matrix. The construction method of the admittance matrix is ​​existing technology and will not be elaborated here. At the same time, the grid connection point bus (i.e., the primary side bus of the DRU converter transformer) is identified as the balancing node.

[0031] Step S2: For each candidate input combination, based on the current candidate input combination, generator data and admittance matrix, repeat the reactive power optimization solution operation to obtain the corresponding optimal reactive power optimization parameters and objective function value, and perform reactive power optimization adjustment based on the candidate input combination and optimal reactive power optimization parameters corresponding to the minimum objective function value. Specifically, different numbers of filters can be deployed to form various feasible operating conditions. Under different candidate deployment combinations, the reactive power supply capacity of the power collection system varies significantly, which in turn changes the reactive power output allocation scheme of the wind turbine, the reactive power regulation capacity occupancy of the auxiliary MMC, and the active power loss of the power collection system.

[0032] Therefore, in order to search for the optimal reactive power scheduling strategy in the global scope, this invention performs traversal calculations on each candidate input combination of the filter. For each candidate input combination, the inner reactive power optimization solution operation is repeatedly executed in combination with the current candidate input combination, generator data and the pre-constructed admittance matrix. During the solution, this invention uses the Sequential Quadratic Programming (SQP) algorithm to solve this nonlinear programming problem, and finally performs reactive power optimization adjustment based on the candidate input combination corresponding to the minimum objective function value and the optimal reactive power optimization parameters.

[0033] The reactive power optimization solution operation includes: Obtain the current reactive power output of the wind turbine and the current voltage amplitude at the grid connection point; wherein, the initial reactive power output of the wind turbine is calculated based on the preset initial power factor, and the initial voltage amplitude at the grid connection point is calculated based on the preset grid connection point boundary voltage; Specifically, the initial reactive power output of the wind turbine and the voltage amplitude at the grid connection point are determined based on the following method: Initially, the wind turbines connected to each node operate according to a preset initial power factor, that is, their reactive power output is determined using a constant power factor method. i The initial reactive power output of the wind turbine is: And limit it to the non-functional capacity range of the corresponding wind turbine: The initial grid connection point voltage amplitude is taken as the per-unit value corresponding to the preset grid connection point boundary voltage, that is: In the formula, Indicates connection to node The initial reactive power output of the wind turbine generator, in Mvar. Indicates connection to node The equivalent active power output of wind turbine units, in MW. This indicates the preset initial power factor of the fan; This represents the set of nodes connected to wind turbine generators. , These represent nodes connected to respectively The preset lower and upper limits of reactive power output of wind turbine generators, in Mvar; This represents the initial grid connection point voltage amplitude, in per-unit values. Indicates the preset grid connection point boundary voltage. This indicates the rated voltage at the grid connection point, with units of kV.

[0034] Construct the coefficient matrix of the current AC power flow linear equation system based on the admittance matrix. Construct the right-hand vector of the current AC power flow linear equation system based on the active power output of the wind turbine, the current reactive power output of the wind turbine and the current voltage amplitude of the grid connection point in the generator data. Perform matrix solution on the current AC power flow linear equation system to obtain the current approximate voltage phasor of the non-grid connection point. Specifically, firstly, the nodal injection power equation is used as the original AC power flow equation, and its mathematical form is: In the formula, This represents the active power injected at node i. This represents the reactive power injected at node i. This represents the voltage magnitude at node i. This represents the voltage magnitude at node j. and Represents the elements in the admittance matrix. This represents the voltage phase angle difference between node i and node j, and n represents the number of nodes.

[0035] Subsequently, the voltage magnitude parameter in this original AC power flow equation is incorporated into the summation symbol, resulting in: by and As independent variables, at the initial point of cold start , By performing a Taylor expansion on the nonlinear terms on the right-hand side of the equation and neglecting higher-order terms, we obtain the following linearized power flow equations: In the formula, k represents the power parameter.

[0036] In the linearized power flow equations described above, voltage magnitude and nodal injected power are naturally decoupled, making them suitable for both power flow calculations and optimization problems. Let As state variables, the above linearized power flow equations can be further written in matrix form: The coefficient matrices are as follows: In the formula, Q represents active power injection, and Q represents reactive power injection. , , , , and Representing the coefficient matrices, State variables representing voltage amplitude, The variable representing the voltage phase angle, The matrix representing the real part of the admittance matrix. The matrix representing the imaginary part of the admittance matrix. Represents a column vector consisting entirely of 1s. This indicates that a diagonal matrix is ​​constructed using vectors as diagonal elements.

[0037] Finally, after eliminating the slack node (i.e., the grid connection point), the known slack node voltage state is... Moving to the right side of the equation, we obtain the state variables of the non-equilibrium nodes. The linear equation system, namely the AC power flow linear equation system mentioned above: In the formula, This represents the coefficient matrix after eliminating the balanced nodes, where N represents the set of unbalanced nodes (i.e., the set of non-connected nodes), and s represents the balanced nodes. This represents the active power injection matrix corresponding to the unbalanced node. This represents the reactive power injection matrix corresponding to the unbalanced node. Represents the coefficient matrix Bank of China's corresponding unbalanced node set The column corresponds to the balanced node. The submatrix represents the voltage state variables of the equilibrium node. Mapping of active power injection at unbalanced nodes; Represents the coefficient matrix Bank of China's corresponding unbalanced node set Column corresponding to the balance node The submatrix represents the voltage state variables of the equilibrium node. Mapping of reactive power injection at unbalanced nodes; Represents a constant vector The corresponding set of unbalanced nodes The subvector formed by the components; Represents a constant vector The corresponding set of unbalanced nodes The subvector formed by the components, This represents the voltage amplitude at the saturation point. This indicates the voltage state of the unbalanced node.

[0038] Specifically, by directly solving the above AC power flow linear equations, the approximate voltage amplitude and approximate voltage phase angle of each node in the collector system can be obtained. Based on the approximate voltage amplitude and approximate voltage phase angle, the approximate voltage phasor can be obtained.

[0039] Based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current voltage amplitude at the grid connection point, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state. If the current solution convergence state is convergence, the current reactive power optimization parameters and the current objective function value are used as the optimal reactive power optimization parameters and objective function value corresponding to the current candidate input combination; otherwise, based on the current objective function value and the current constraint violation, the updated wind turbine reactive power output and grid connection point voltage amplitude are calculated.

[0040] Specifically, the updated reactive power output of the wind turbine and the voltage amplitude at the grid connection point are calculated based on the following method: This invention employs a sequential quadratic programming algorithm for iterative updates, denoted as . (i.e., the independent decision variables in the current reactive power optimization parameters). In the... Next iteration point At, with the objective function gradient Inequality constraints Jacobian matrix And the positive definite approximation of the Lagrange function Hessian matrix Construct the following quadratic programming subproblem and solve it to obtain the search direction. : Subsequently, along the search direction Perform a one-dimensional line search to determine the step size that allows the value function to decrease sufficiently. And update the optimization variables as follows: Depend on The updated reactive power output of the wind turbine is obtained through separation. and the updated grid connection point voltage amplitude The current reactive power output of the wind turbine and the voltage amplitude at the current grid connection point are used as the basis for the next reactive power optimization solution operation.

[0041] In the formula, Represents the vector of optimization variables; Indicates the first Positive definite approximation of the Hessian matrix of the Lagrange function in the next iteration (obtained by updating the quasi-Newton method); Indicates the first The search direction for the next iteration; d represents the search direction; The first part represents the multi-source reactive power cooperative optimization model. Inequality constraint functions, This represents the total number of inequality constraints. This represents the lower bound vector of the optimization variables; The upper bound vectors of the optimization variables are represented by the wind turbine's no-function capacity constraint and the grid connection point boundary voltage constraint. Indicates the first The step size of the line search in the next iteration; superscript Indicates the first The next iteration.

[0042] To illustrate and verify the effectiveness of the method proposed in this invention, a case study is conducted on a 2000 MW offshore wind farm in a coastal province that transmits power via a DRU-MMC DC transmission system. The overall system structure is as follows: After the offshore wind farm's power is collected by a 66kV AC collector system, it is rectified by a DRU and sent to a ±500 kV DC system, which then transmits the power to the AC grid via an onshore inverter station. An auxiliary MMC is installed offshore, weakly connected to the DRU grid connection point via a 66 kV AC bus, for black start, near-zero power operation maintenance, and reactive power voltage support of the wind farm.

[0043] To comprehensively evaluate the applicability of the proposed method under different wind power output levels, 21 power levels (5% step size) were set for the total active power output of the wind farm, ranging from 0% to 100% of the rated power. At each power level, the benchmark method (i.e., the reactive power optimization method based on nonlinear AC power flow iteration in the prior art) and the method of this invention were used to solve the problem. The differences in the accuracy and computational efficiency of the two methods were compared and analyzed. A schematic diagram comparing the active power output of the power collection system is shown below. Figure 2 As shown in the diagram, the reactive power demand comparison diagram on the DRU converter side is as follows: Figure 3 As shown in the diagram, the net reactive power comparison at the grid connection point is as follows: Figure 4 As shown. Figure 2 , Figure 3 and Figure 4 The “benchmark algorithm” mentioned above is denoted as the benchmark method, and the “linearization algorithm” is denoted as the method proposed in this invention.

[0044] Specifically, from Figure 2As can be seen, within the full power range of 0% to 100% of rated power, the active power output of the power collection system obtained by the method of this invention is highly consistent with that obtained by the benchmark method. The normalized deviation of the output active power based on the total active power setpoint of the wind farm is used as a measure. The maximum normalized deviation is 0.173% (corresponding to a maximum absolute deviation of 3.479 MW), and the average normalized deviation is 0.070%. The maximum deviation occurs at full power output (1.00 pu). The results show that the linearized power flow model is basically consistent with the nonlinear power flow calculation results in terms of the equivalent accuracy of the boundary active power.

[0045] Specifically, from Figure 3 As can be seen, the reactive power demand obtained by the two methods on the DRU converter side shows a consistent overall trend, exhibiting a monotonically increasing characteristic as the active power output of the wind turbine increases. Measured by the percentage deviation of symmetry, the maximum symmetry deviation is 8.216% (corresponding to a maximum absolute deviation of 17.727 Mvar), and the average symmetry deviation is 3.771%. The maximum deviation occurs in the low active power output range (0.20 pu), where the absolute reactive power demand is relatively small, thus amplifying the relative deviation. In the medium-to-high active power range, the reactive power demand curves of the two methods closely match.

[0046] Specifically, the net reactive power at the grid connection point is jointly determined by the filter output, the reactive power output of the auxiliary MMC, and the reactive power demand of the DRU. From... Figure 4 As can be seen, after normalizing to the available reactive power support capacity (total filter capacity + auxiliary MMC capacity = 330 Mvar), the maximum normalization deviation between the two methods is 13.481% (corresponding to a maximum absolute deviation of 44.489 Mvar), and the average normalization deviation is 4.325%. The maximum deviation occurs at 0.65 pu, mainly because the two methods selected different filter operation combinations near this power level, resulting in a step difference in net reactive power caused by the switching of discrete variables. Except for the filter switching jump condition, the net reactive power trends of the two methods are consistent.

[0047] Meanwhile, under the same 21 power level conditions, the total computation time of the benchmark method and the method of this invention were recorded respectively, and the results are shown in the table below: As can be seen from the table above, the method proposed in this invention achieves a computational speedup of approximately 17 times by replacing iterative solutions with direct matrix solutions in the AC collector system optimization process. This avoids the overhead of power flow iteration in each objective function and constraint evaluation, while maintaining acceptable engineering accuracy. This improvement in computational efficiency provides an important computational foundation for large-scale reactive power optimization in annual multi-scenario time-series simulations.

[0048] In a preferred embodiment, based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current grid connection point voltage amplitude, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor, the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state are calculated and determined, including: Obtain the reactive power penalty weights of the auxiliary MMC and the reactive power penalty weights of the wind turbine. Based on the preset rated reactive power capacity of the auxiliary MMC, the reactive power penalty weight of the auxiliary MMC, and the reactive power penalty weight of the wind turbine, the objective function of the multi-source reactive power collaborative optimization model is constructed with the goal of minimizing the grid loss of the power collection system and maximizing the dynamic reactive power margin of the auxiliary MMC. Specifically, the objective function mentioned above is: In the formula, J represents the objective function. This indicates that there is always a loss in the active network. Indicates the reactive power penalty weight of the auxiliary MMC. This indicates the reactive power required to assist MMC. This indicates the preset rated reactive power capacity of the auxiliary MMC. This indicates the reactive power penalty weight of the wind turbine. This indicates the total number of wind turbines. Indicates connection to node The reactive power output of the wind turbine units Indicates connection to node The reactive power capacity of wind turbine units, This indicates the corrected reactive power at the grid connection point boundary. This indicates the reactive power requirement at the DRU grid connection point, that is, the reactive power required by the DRU at the grid connection point. This indicates the reactive power output of the AC filter. This indicates the number of input groups in the candidate input combinations of the filter. This represents the reactive power capacity of a single AC filter, measured in Mvar.

[0049] Based on the preset node voltage amplitude limit, the preset rated reactive power capacity of the auxiliary MMC, the preset branch apparent power rated capacity, and the preset wind turbine reactive power output limit, the constraints of the multi-source reactive power collaborative optimization model are constructed. Specifically, the above constraints include: collector system node voltage constraints, branch load rate constraints, auxiliary MMC reactive power capacity constraints, DRU DC voltage margin constraints, and wind turbine reactive power capacity constraints. Among these, the collector system node voltage constraints are: In the formula, This represents the minimum value among the preset node voltage amplitude limits. This indicates the maximum value among the preset node voltage amplitude limits.

[0050] It should be noted that the nodes in the above-mentioned current collector system node voltage constraints include grid-connected points and non-grid-connected points. For grid-connected points, the parameter " "That is, substitute the voltage amplitude at the grid connection point; for non-grid connection points, the parameter..." "Substitute the voltage amplitude of the non-grid-connected point into the voltage amplitude of the previously known balanced node voltage state."

[0051] Specifically, the branch load rate constraint is that the apparent power of each branch does not exceed the corresponding preset branch apparent power rated capacity.

[0052] Specifically, the reactive power capacity constraint of the auxiliary MMC is expressed as follows: In the formula, This indicates the default minimum reactive power output of the auxiliary MMC.

[0053] Specifically, the DC voltage margin constraint of the DRU is that the DC voltage margin is 0, that is, the 12-pulse rectifier voltage capability of the DRU is equal to the rectifier terminal voltage required by the DC line equation.

[0054] Specifically, the no-work-force constraint of a wind turbine is represented as follows: In the formula, This represents the minimum value among the preset reactive power output limits of the wind turbine connected to node i. This represents the maximum value among the preset reactive power output limits of the fan connected to node i.

[0055] Based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, current objective function value, and current constraint violation amount. Based on the current reactive power optimization parameters, the current objective function value, and the current constraint violation, the change magnitude of the current optimization parameters and the change magnitude of the current objective function are calculated. If the magnitude of the change in the current optimization parameters, the magnitude of the change in the current objective function, and the current constraint violation all do not exceed the corresponding preset thresholds, then the current solution convergence state is converged; otherwise, the current solution convergence state is non-converged.

[0056] Specifically, the current reactive power optimization parameters, current objective function value, and current constraint violation amount obtained in this iteration are subtracted from the corresponding reactive power optimization parameters, objective function value, and constraint violation amount obtained in the previous iteration, respectively, to obtain the current reactive power optimization parameters, current objective function value, and current constraint violation amount.

[0057] Subsequently, a corresponding threshold is set for each amplitude value. When all amplitude values ​​do not exceed the corresponding preset threshold, it indicates that the current SQP optimization iteration has converged, and the current iteration is terminated. The current constraint violation and each change amplitude value are calculated based on the following method: All inequality constraints of the multi-source reactive power co-optimization model are uniformly expressed as follows: ( This encompasses the node voltage constraints of the collector system, branch load rate constraints, auxiliary MMC reactive power capacity constraints, and DRU DC voltage margin constraints. The current constraint violation in the next iteration is the maximum value of the excesses of all inequality constraints: The current magnitude of change in the optimization parameters and the current magnitude of change in the objective function are as follows: When both conditions are met , , If the current solution is convergent, it is determined that the solution is convergent; otherwise, it is non-convergent.

[0058] In the formula, Indicates the first The current constraint violation in the next iteration; Indicates the first The optimized variable vector for the next iteration. Indicates the first The objective function value of the next iteration; This indicates the magnitude of the change in the current optimization parameters. This represents the magnitude of the change in the current objective function; , , These represent the preset thresholds corresponding to the three change magnitude values ​​mentioned above; The infinite norm of a vector is the maximum absolute value of all its components. This indicates that the quantity is taken and The larger one.

[0059] In this preferred embodiment, the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state are calculated and determined based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current grid connection point voltage amplitude, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor.

[0060] In another preferred embodiment, based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor, the current reactive power optimization parameters, current objective function value, and current constraint violation are calculated and determined, including: Based on the current approximate voltage phasor, admittance matrix, and current candidate input combinations, the current node precise re-injection power, current total active power loss, current branch apparent power, and current grid connection point original boundary power are calculated. Specifically, using the approximate voltage phasors and network admittance matrix obtained from the solution for non-grid-connected points, combined with the reactive power output conditions corresponding to the current candidate AC filter combinations, forward algebraic operations are performed by substituting them into the accurate power flow equation. First, the accurate complex-injected power at each node is solved. Based on this, the total active power loss of the collector system and the apparent power of each branch are statistically analyzed. Simultaneously, the original boundary power of the grid-connected points before deviation correction is implemented is calculated. This process only performs power calculations under known voltages, eliminating the need for nonlinear iterations and quickly obtaining various electrical quantities for subsequent constraint verification and objective function evaluation.

[0061] The original boundary power of the current grid connection point is corrected based on the active power output of the wind turbine, the current reactive power output of the wind turbine, and the current node precise re-injection power, to obtain the corrected current grid connection point boundary power and the current grid connection point active power sent into the DRU. Specifically, based on the active power output of the wind turbines, the current reactive power output of the wind turbines, and the calculated precise reinjection power at the nodes, the power imbalance deviation of all nodes in the network is calculated. All power deviations are then uniformly aggregated to the balancing node, and compensation correction is applied to the original boundary power of the grid connection point to obtain the corrected boundary power. The active component is extracted from this correction, which is the current active power delivered to the DRU at the grid connection point. This correction process eliminates the power imbalance problem caused by the linearized power flow approximation, ensuring power matching at the AC / DC interfaces.

[0062] Based on the current active power and voltage amplitude of the DRU at the current grid connection point, the current DC voltage margin and reactive power demand at the current DRU grid connection point are calculated. Specifically, based on the current active power and voltage amplitude at the grid connection point fed into the DRU, and combined with the inherent parameters of the DRU equipment, the current DC voltage margin is calculated. Simultaneously, based on the active power and grid connection voltage amplitude, the reactive power consumption generated during the commutation process is calculated to obtain the current reactive power demand at the DRU grid connection point.

[0063] Based on the current reactive power demand of the DRU grid connection point, the corrected current grid connection point boundary power, and the current candidate input combination, the reactive power required by the current auxiliary MMC is calculated. Specifically, the formula for calculating the reactive power required to assist MMC is as follows: Based on the reactive power required by the current auxiliary MMC, the current candidate input combination, the current total active power loss, the current reactive power of the wind turbine, the voltage amplitude of the non-grid-connected point in the bus data, the voltage amplitude of the current grid-connected point, the current apparent power of the branch, the current DC voltage margin, the objective function and the constraints, the current objective function value and the current constraint violation amount are calculated. Specifically, by substituting the current reactive power required by the auxiliary MMC, the current candidate input combination, the current total active power loss, the current reactive power of the wind turbine, the voltage amplitude at the non-grid connection point in the bus data, the voltage amplitude at the current grid connection point, the apparent power of the current branch, and the current DC voltage margin into the constructed objective function and constraints, the objective function value and constraint violation amount can be calculated and determined.

[0064] The current reactive power output of the wind turbine, the current voltage amplitude at the grid connection point, and the reactive power output required by the current auxiliary MMC are used as the current reactive power optimization parameters.

[0065] Specifically, the aforementioned current reactive power optimization parameters and the current candidate input combination together constitute the complete adjustment result of multi-source reactive power collaborative optimization under this candidate input combination, where the reactive power switching amount of the AC filter corresponding to the current candidate input combination is... .

[0066] In this preferred embodiment, the current reactive power optimization parameters, the current objective function value, and the current constraint violation amount are calculated and determined based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor.

[0067] In another preferred embodiment, based on the current approximate voltage phasor, admittance matrix, and current candidate input combinations, the current node's precise re-injection power, current total active power loss, current branch apparent power, and current grid connection point's original boundary power are calculated, including: The precise complex injection power of the current node is calculated based on the current approximate voltage phasor and the preset precise node power equation constructed based on the admittance matrix. Specifically, the exact re-injection power at the node is calculated based on the following formula: In the formula, This represents the precise re-injection power at node i, in MVA. This represents the system's base power capacity, measured in MVA. Represents a node The approximate voltage phasor, i.e. ,in For nodes Approximate voltage amplitude, For nodes Approximate voltage phase angle; Represents the first in the bus admittance matrix Line 1 Column elements, Represents a node The approximate voltage phasor, i.e. ,in The approximate voltage magnitude at node j, For nodes The approximate voltage phase angle. This represents a column vector consisting of the precise re-injected power at each node. This represents the exact complex injection power at n distinct nodes. This represents a column vector composed of approximate voltage phasors at each node. This represents the approximate voltage phasor of n distinct nodes. Represents the bus admittance matrix. The superscript indicates the element-wise conjugate of a complex number or complex vector. This indicates transpose.

[0068] Based on the current approximate voltage phasor and admittance matrix, the complex power at the beginning of the current branch and the complex power at the end of the current branch are calculated. Specifically, firstly, using the branch head admittance matrix and branch tail admittance matrix in the constructed admittance matrix, the phasor of the injected current at the head and tail of each branch are calculated: In the formula, This represents the column vector formed by the phasors of the current injected at the beginning of each branch. This represents the column vector formed by the phasors of the injected currents at the ends of each branch. This represents the admittance matrix at the beginning of the branch. This represents the admittance matrix at the end of the branch.

[0069] Subsequently, based on the system power reference capacity, the node approximate voltage phasor, the phasor of the current injected at the beginning and end of each branch, the complex power at the beginning and end of the branch are calculated: In the formula, This represents the complex power at the beginning of branch l. This represents the complex power at the end of branch l. This represents the approximate voltage phasor of the busbar at the beginning of branch l. The approximate voltage phasor of the terminal busbar of branch l is represented. The conjugate of the injected current phasor of the busbar at the beginning of branch l is represented. The conjugate of the injected current phasor of the terminal busbar of branch l is represented. Indicates the number of branches.

[0070] Take the real part of the sum of the complex power at the beginning of the current branch and the complex power at the end of the current branch to obtain the active power loss of the current branch; Specifically, the active power loss of each branch is the sum of the active power at the beginning and the active power at the end of the branch. Therefore, by taking the real part of the sum of the complex power at the beginning and the complex power at the end of the branch, the active power loss of the branch can be obtained. In the formula, This represents the active power loss of branch l. Indicates the real part.

[0071] Based on the non-negativity of the sum of the current active power network losses of all branches, the small negative network losses that may be introduced by the linear approximation under light load conditions are eliminated, and the current total active power network loss is obtained. Specifically, the total active power loss is calculated using the following formula: In the formula, This indicates that there is always a loss in the network.

[0072] The apparent power of the current branch is calculated based on the complex power at the beginning and end of the current branch. Specifically, the apparent power of each branch is taken as the larger of its apparent power at the beginning and the apparent power at the end, and is used for the evaluation of the load factor constraint of subsequent branches: In the formula, This represents the apparent power of branch l, in MVA. This indicates taking the modulus of a complex number.

[0073] The precise re-injection power of the current grid connection point is extracted from the precise re-injection power of the current node. The real part of the precisely re-injected power at the current grid connection point is taken as the original boundary active power of the current grid connection point, and the imaginary part of the precisely re-injected power at the current grid connection point is taken as the original boundary reactive power of the current grid connection point, and then the original boundary power of the current grid connection point is obtained.

[0074] Specifically, the original boundary power at the grid connection point is determined by the precise re-injection power at the grid connection point. Following the equivalent modeling method of the AC filter at the grid connection point using a fixed reactive power injection approach, the original boundary active power and original boundary reactive power on the collector system side at the grid connection point are as follows: In the formula, This indicates the active power at the original boundary of the grid connection point. This represents the reactive power at the original boundary of the grid connection point. This indicates taking the imaginary part of a complex number. This indicates the precise re-injection power at the grid connection point.

[0075] In this preferred embodiment, the current node's precise re-injection power, current total active power loss, current branch apparent power, and current grid connection point's original boundary power are calculated based on the current approximate voltage phasor, admittance matrix, and current candidate input combination.

[0076] In another preferred embodiment, the original boundary power of the current grid connection point is corrected based on the active power output of the wind turbine, the current reactive power output of the wind turbine, and the precise re-injection power of the current node, to obtain the corrected boundary power of the current grid connection point and the active power of the current grid connection point fed into the DRU, including: Based on the current node's precise re-injection power, the active power output of the wind turbine, and the current reactive power output of the wind turbine, the precise injection active power deviation and the precise injection reactive power deviation of the current non-grid-connected point are calculated. Specifically, for each non-grid-connected node, calculate the active power deviation and reactive power deviation between the precise injected power obtained by back-substituting the precise network equation and the specified injected power of that node: In the formula, This represents the precise injected active power deviation at node i. This represents the exact re-injection power at node i. This represents the equivalent active power output of the wind turbine connected to node i.

[0077] It should be noted that in this invention, for non-grid-connected nodes that are not connected to wind turbines, the corresponding values ​​are taken as follows: , .

[0078] The precise injection active power deviation and precise injection reactive power deviation of all current non-grid-connected points are summed to obtain the current total network active power deviation and the current total network reactive power deviation. Specifically, the active power deviation and reactive power deviation of the entire network are calculated based on the following formulas: In the formula, This indicates the active power deviation across the entire network, in MW. This indicates the reactive power deviation of the entire network, in Mvar.

[0079] The current active power deviation of the entire network is superimposed on the original boundary active power of the current grid connection point to obtain the corrected boundary active power of the current grid connection point; Specifically, the corrected active power at the grid connection point boundary is calculated based on the following formula: In the formula, This represents the corrected active power at the grid connection point boundary, in MW.

[0080] The current reactive power deviation of the entire network is superimposed on the original boundary reactive power of the current grid connection point to obtain the corrected boundary reactive power of the current grid connection point; Specifically, the corrected reactive power at the grid connection point boundary is calculated based on the following formula: In the formula, This represents the corrected reactive power at the grid connection point boundary, in Mvar.

[0081] Preferably, based on this correction process, the specified injected power of the unbalanced node and the corrected boundary injected power of the balanced node are made to satisfy the overall power balance again, so that the corrected grid connection point boundary power is consistent with the settlement caliber based on the complete nonlinear AC power flow.

[0082] Based on the corrected active power and reactive power at the current grid connection point boundary, the corrected current grid connection point boundary power is obtained. Specifically, the corrected active power and the corrected reactive power at the current grid connection point boundary together constitute the corrected current grid connection point boundary power.

[0083] Take the negative of the corrected current grid connection point boundary active power to obtain the current grid connection point active power fed into the DRU.

[0084] Specifically, the active power at the grid connection point fed into the DRU is determined by the following formula: In the formula, This indicates the active power supplied to the grid connection point of the DRU.

[0085] In this preferred embodiment, the original boundary power of the current grid connection point is corrected based on the active power output of the wind turbine, the current reactive power output of the wind turbine, and the current node's precise re-injection power, to obtain the corrected current grid connection point boundary power and the current grid connection point active power fed into the DRU.

[0086] In another preferred embodiment, based on the current active power and voltage amplitude at the grid connection point fed into the DRU, the current DC voltage margin and reactive power demand at the current DRU grid connection point are calculated, including: Obtain the current valve-side AC line voltage and commutation reactance; Using the current grid-connected active power and current grid-connected voltage amplitude as inputs to the DRU, and the DC current, valve-side voltage phase angle, and valve-side voltage amplitude as unknown variables, a steady-state interface model of the DRU converter is constructed. The steady-state interface model of the DRU converter is solved to obtain the current DC current; Specifically, the steady-state interface model of the entire DRU converter takes the current grid-connected active power and voltage amplitude at the current grid connection point as inputs, and the DC current, the phase angle of the valve-side voltage of the DRU converter transformer, and the voltage amplitude at the valve side as unknown variables. The corresponding nonlinear equations are expressed as follows: In the formula, This indicates the three-phase complex power on the valve side of the DRU converter transformer. This indicates the three-phase complex power at the grid connection point of the power collection system. This represents the total active power of the bipolar DC side of the DRU. This indicates the reactive power required for the DRU commutation process.

[0087] It should be noted that the DRU converter transformer adopts a steady-state equivalent model of "ideal turns ratio series valve-side equivalent leakage impedance". Taking the phase angle of the grid connection point voltage as a reference, the phase voltage phasor at the grid connection point (collector system side) is... and valve-side phase voltage phasor They are respectively: Valve-side injected current phasor and the phasor of the injected current at the grid connection point They are respectively: Valve-side three-phase complex power Three-phase power at grid connection point They are respectively: As can be seen from the above equation, the phase angle of the valve-side voltage of the DRU converter transformer is determined by the parameters. This indicates that the amplitude of the valve-side voltage of the DRU converter transformer is determined by parameters. express( ,in (This refers to the per-unit value of the valve-side voltage amplitude). Therefore, the unknown variable in the steady-state interface model is the DC current. Valve-side voltage phase angle and valve side voltage amplitude (Equivalent land is in per unit value) There are three (characteristics), each corresponding to one of the three nonlinear equations mentioned above, thus determining the active power at the current grid connection point given the input to the DRU. and the current grid connection point voltage amplitude Under the given conditions, the steady-state operating point of the DRU can be uniquely determined.

[0088] In the formula, This represents the phase voltage phasor on the grid connection point side. Indicates the phase voltage phasor on the valve side; This indicates the voltage amplitude at the grid connection point (per unit value). Indicates the rated line voltage at the grid connection point; Indicates the amplitude of the AC line voltage on the valve side. Indicates the phase angle of the valve-side voltage. This indicates the per-unit value of the valve-side voltage amplitude. Indicates the rated line voltage on the valve side; This represents the phasor of the injected current on the valve side. This indicates the phasor of the injected current at the grid connection point; This represents the ideal turns ratio of the DRU converter transformer, which is the ratio of the rated line voltage on the grid connection side to the rated line voltage on the valve side. ; This represents the equivalent leakage impedance of the DRU converter transformer referred to the valve side; The conjugate of the complex number is represented. In the above nonlinear equation system, the first equation represents the active power balance relationship on the DRU valve side, the second equation represents the reactive power balance relationship on the DRU valve side, and the third equation represents the matching of the active power on the grid connection point of the collector system with the current grid connection point active power fed into the DRU by the AC collector system. The above three equations together determine the steady-state operating point of the DRU under the given current grid connection point active power fed into the DRU and grid connection point voltage amplitude.

[0089] Specifically, the DC side adopts a unified definition method for unipolar voltage, per-pole current, and total bipolar power. Let... This is the unipolar DC voltage at the rectifier terminal. It is a unipolar direct current (i.e., the direct current mentioned above). The receiving end is a single-pole DC voltage. For the resistance of a unipolar DC line, then: Meanwhile, the reactive power required for the DRU commutation process is determined based on the commutation overlap angle and the power factor angle, and the commutation overlap angle satisfies: In the formula, Indicates the commutation overlap angle. Indicates the AC line voltage on the valve side. This indicates the commutation reactance.

[0090] The power factor angle satisfies: In the formula, It represents the power factor angle.

[0091] Therefore, the reactive power required for the DRU commutation process can be expressed by the following formula: Therefore, by combining the above nonlinear equations, the calculation expression for the total active power of the DRU DC side bipolar, and the calculation expression for the reactive power required for the DRU commutation process, the DC current can be solved.

[0092] The current DC voltage margin is calculated based on the current DC current, the current AC line voltage on the valve side, and the commutation reactance. Specifically, after solving for the DC current, the power factor angle and commutation overlap angle are further calculated using the aforementioned formulas.

[0093] Subsequently, the DC voltage margin of the DRU is defined as the difference between the DRU's twelve-pulse rectifier voltage capability and the rectifier terminal voltage required by the DC line equation, and can therefore be calculated based on the following formula: In the formula, Indicates DC voltage margin. This indicates the twelve-pulse rectified voltage capability of the DRU. The voltage conversion coefficient representing the AC line voltage to the ideal no-load DC voltage on the valve side of the DRU twelve-pulse rectifier bridge is a preset constant determined by the rectifier bridge topology and the converter transformer wiring method, and its value satisfies... .

[0094] Based on the corrected active power at the current grid connection point boundary, the three-phase complex power at the current grid connection point is calculated. Take the imaginary part of the three-phase complex power at the current grid connection point to obtain the reactive power demand at the current DRU grid connection point.

[0095] Specifically, the reactive power demand at the DRU grid connection point is calculated based on the following formula: In the formula, This indicates the reactive power demand at the DRU grid connection point. This indicates the three-phase complex power at the grid connection point.

[0096] In this preferred embodiment, the current DC voltage margin and the current reactive power demand of the DRU grid connection point are calculated based on the current active power and voltage amplitude of the DRU fed into the grid connection point.

[0097] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments.

[0098] like Figure 5 As shown, an embodiment of the present invention provides a reactive power collaborative optimization device for a multi-terminal heterogeneous power collection system for offshore wind power, comprising: Data acquisition module 101 and reactive power optimization and adjustment module 102; The data acquisition module 101 is used to acquire bus data, branch data, generator data, and several candidate input combinations of AC filters of the offshore wind power collection system, and to construct an admittance matrix based on the bus data and branch data. The reactive power optimization and adjustment module 102 is used to repeatedly perform reactive power optimization solution operation for each candidate input combination based on the current candidate input combination, generator data and admittance matrix to obtain the corresponding optimal reactive power optimization parameters and objective function value, and to perform reactive power optimization adjustment based on the candidate input combination and optimal reactive power optimization parameters corresponding to the minimum objective function value. The reactive power optimization solution operation includes: Obtain the current reactive power output of the wind turbine and the current voltage amplitude at the grid connection point; wherein, the initial reactive power output of the wind turbine is calculated based on the preset initial power factor, and the initial voltage amplitude at the grid connection point is calculated based on the preset grid connection point boundary voltage; Construct the coefficient matrix of the current AC power flow linear equation system based on the admittance matrix. Construct the right-hand vector of the current AC power flow linear equation system based on the active power output of the wind turbine, the current reactive power output of the wind turbine and the current voltage amplitude of the grid connection point in the generator data. Perform matrix solution on the current AC power flow linear equation system to obtain the current approximate voltage phasor of the non-grid connection point. Based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current voltage amplitude at the grid connection point, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state. If the current solution convergence state is convergence, the current reactive power optimization parameters and the current objective function value are used as the optimal reactive power optimization parameters and objective function value corresponding to the current candidate input combination; otherwise, based on the current objective function value and the current constraint violation, the updated wind turbine reactive power output and grid connection point voltage amplitude are calculated.

[0099] In a preferred embodiment, the reactive power optimization and adjustment module 102 includes: The system includes a weight acquisition unit, an objective function construction unit, a constraint construction unit, a data calculation unit, an amplitude calculation unit, and a convergence judgment unit. The weight acquisition unit is used to acquire the reactive power penalty weight of the auxiliary MMC and the reactive power penalty weight of the wind turbine. The objective function construction unit is used to construct the objective function of a multi-source reactive power collaborative optimization model with the objectives of minimizing grid loss of the power collection system and maximizing the dynamic reactive power margin of the auxiliary MMC, based on the preset rated reactive power capacity of the auxiliary MMC, the reactive power penalty weight of the auxiliary MMC and the reactive power penalty weight of the wind turbine. The constraint construction unit is used to construct the constraint conditions of the multi-source reactive power collaborative optimization model based on the preset node voltage amplitude limit, the preset rated reactive power capacity of the auxiliary MMC, the preset branch apparent power rated capacity, and the preset wind turbine reactive power output limit. The data calculation unit is used to calculate and determine the current reactive power optimization parameters, the current objective function value, and the current constraint violation amount based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor. The amplitude calculation unit is used to calculate the amplitude value of the change in the current optimization parameters and the amplitude value of the change in the current objective function based on the current reactive power optimization parameters, the current objective function value and the current constraint violation amount; The convergence judgment unit is used to determine if the current solution convergence state is converged if the change magnitude of the current optimization parameter, the change magnitude of the current objective function, and the current constraint violation do not exceed the corresponding preset threshold; otherwise, the current solution convergence state is non-convergent.

[0100] It should be noted that the device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationship between modules indicates that they have a communication connection, which can be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without creative effort. The above schematic diagram is merely an example of a reactive power collaborative optimization device for a multi-terminal heterogeneous power collection system in offshore wind power, and does not constitute a limitation on such a device. It may include more or fewer components than illustrated, or combine certain components, or use different components.

[0101] Based on the above method embodiments, the present invention provides corresponding terminal device embodiments.

[0102] Another embodiment of the present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power described in any embodiment of the present invention.

[0103] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the device. The aforementioned terminal devices may be computing devices such as desktop computers, laptops, handheld computers, and cloud servers. These devices may include, but are not limited to, processors and memory. The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. This processor is the control center of the device, connecting various parts of the device via various interfaces and lines. The aforementioned memory can be used to store the aforementioned computer programs and / or modules. The aforementioned processor implements various functions of the aforementioned device by running or executing the computer programs and / or modules stored in the aforementioned memory, and by calling data stored in the memory. The aforementioned memory may mainly include a program storage area and a data storage area, wherein the program storage area may store the operating system, at least one application program required for a function, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0104] Based on the above method embodiments, the present invention provides corresponding storage medium embodiments.

[0105] Another embodiment of the present invention provides a storage medium including a stored computer program, wherein, when the computer program is running, it controls the device where the storage medium is located to execute the reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system of offshore wind power described in any embodiment of the present invention.

[0106] In this embodiment, the storage medium is a computer-readable storage medium, and the computer program includes computer program code, which may be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium may include any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0107] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for reactive power collaborative optimization of a multi-terminal heterogeneous power collection system for offshore wind power, characterized in that, include: Obtain bus data, branch data, generator data, and several candidate combinations of AC filters for offshore wind power collection systems, and construct an admittance matrix based on the bus data and branch data. For each candidate input combination, based on the current candidate input combination, generator data, and admittance matrix, the reactive power optimization solution operation is repeatedly executed to obtain the corresponding optimal reactive power optimization parameters and objective function value. Then, reactive power optimization adjustment is performed based on the candidate input combination and optimal reactive power optimization parameters corresponding to the minimum objective function value. The reactive power optimization solution operation includes: Obtain the current reactive power output of the wind turbine and the current voltage amplitude at the grid connection point; wherein, the initial reactive power output of the wind turbine is calculated based on the preset initial power factor, and the initial voltage amplitude at the grid connection point is calculated based on the preset grid connection point boundary voltage; Construct the coefficient matrix of the current AC power flow linear equation system based on the admittance matrix. Construct the right-hand vector of the current AC power flow linear equation system based on the active power output of the wind turbine, the current reactive power output of the wind turbine and the current voltage amplitude of the grid connection point in the generator data. Perform matrix solution on the current AC power flow linear equation system to obtain the current approximate voltage phasor of the non-grid connection point. Based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current voltage amplitude at the grid connection point, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state. If the current solution convergence state is convergence, the current reactive power optimization parameters and the current objective function value are used as the optimal reactive power optimization parameters and objective function value corresponding to the current candidate input combination; otherwise, based on the current objective function value and the current constraint violation, the updated wind turbine reactive power output and grid connection point voltage amplitude are calculated.

2. The reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power according to claim 1, characterized in that, Based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current grid connection point voltage amplitude, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor, the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state are calculated and determined, including: Obtain the reactive power penalty weights of the auxiliary MMC and the reactive power penalty weights of the wind turbine. Based on the preset rated reactive power capacity of the auxiliary MMC, the reactive power penalty weight of the auxiliary MMC, and the reactive power penalty weight of the wind turbine, the objective function of the multi-source reactive power collaborative optimization model is constructed with the goal of minimizing the grid loss of the power collection system and maximizing the dynamic reactive power margin of the auxiliary MMC. Based on the preset node voltage amplitude limit, the preset rated reactive power capacity of the auxiliary MMC, the preset branch apparent power rated capacity, and the preset wind turbine reactive power output limit, the constraints of the multi-source reactive power collaborative optimization model are constructed. Based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, current objective function value, and current constraint violation amount. Based on the current reactive power optimization parameters, the current objective function value, and the current constraint violation, the change magnitude of the current optimization parameters and the change magnitude of the current objective function are calculated. If the magnitude of the change in the current optimization parameters, the magnitude of the change in the current objective function, and the current constraint violation all do not exceed the corresponding preset thresholds, then the current solution convergence state is converged; otherwise, the current solution convergence state is non-converged.

3. The reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power according to claim 2, characterized in that, Based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, current objective function value, and current constraint violation, including: Based on the current approximate voltage phasor, admittance matrix, and current candidate input combinations, the current node precise re-injection power, current total active power loss, current branch apparent power, and current grid connection point original boundary power are calculated. The original boundary power of the current grid connection point is corrected based on the active power output of the wind turbine, the current reactive power output of the wind turbine, and the current node precise re-injection power, to obtain the corrected current grid connection point boundary power and the current grid connection point active power sent into the DRU. Based on the current active power and voltage amplitude of the DRU at the current grid connection point, the current DC voltage margin and reactive power demand at the current DRU grid connection point are calculated. Based on the current reactive power demand of the DRU grid connection point, the corrected current grid connection point boundary power, and the current candidate input combination, the reactive power required by the current auxiliary MMC is calculated. Based on the reactive power required by the current auxiliary MMC, the current candidate input combination, the current total active power loss, the current reactive power of the wind turbine, the voltage amplitude of the non-grid-connected point in the bus data, the voltage amplitude of the current grid-connected point, the current apparent power of the branch, the current DC voltage margin, the objective function and the constraints, the current objective function value and the current constraint violation amount are calculated. The current reactive power output of the wind turbine, the current voltage amplitude at the grid connection point, and the reactive power output required by the current auxiliary MMC are used as the current reactive power optimization parameters.

4. The reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power according to claim 3, characterized in that, Based on the current approximate voltage phasor, admittance matrix, and current candidate input combinations, the current node's precise re-injection power, current total active power loss, current branch apparent power, and current grid connection point's original boundary power are calculated, including: The precise complex injection power of the current node is calculated based on the current approximate voltage phasor and the preset precise node power equation constructed based on the admittance matrix. Based on the current approximate voltage phasor and admittance matrix, the complex power at the beginning of the current branch and the complex power at the end of the current branch are calculated. Take the real part of the sum of the complex power at the beginning of the current branch and the complex power at the end of the current branch to obtain the active power loss of the current branch; Based on the non-negative sum of the current active power network losses of all branches, the current total active power network loss is obtained; The apparent power of the current branch is calculated based on the complex power at the beginning and end of the current branch. The precise re-injection power of the current grid connection point is extracted from the precise re-injection power of the current node. The real part of the precisely re-injected power at the current grid connection point is taken as the original boundary active power of the current grid connection point, and the imaginary part of the precisely re-injected power at the current grid connection point is taken as the original boundary reactive power of the current grid connection point, and then the original boundary power of the current grid connection point is obtained.

5. The reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power according to claim 4, characterized in that, Based on the active power output of the wind turbine, the current reactive power output of the wind turbine, and the current node's precise re-injection power corresponding to the original boundary power of the current grid connection point, the corrected current grid connection point boundary power and the current grid connection point active power fed into the DRU are obtained, including: Based on the current node's precise re-injection power, the active power output of the wind turbine, and the current reactive power output of the wind turbine, the precise injection active power deviation and the precise injection reactive power deviation of the current non-grid-connected point are calculated. The precise injection active power deviation and precise injection reactive power deviation of all current non-grid-connected points are summed to obtain the current total network active power deviation and the current total network reactive power deviation. The current active power deviation of the entire network is superimposed on the original boundary active power of the current grid connection point to obtain the corrected boundary active power of the current grid connection point; The current reactive power deviation of the entire network is superimposed on the original boundary reactive power of the current grid connection point to obtain the corrected boundary reactive power of the current grid connection point; Based on the corrected active power and reactive power at the current grid connection point boundary, the corrected current grid connection point boundary power is obtained. Take the negative of the corrected current grid connection point boundary active power to obtain the current grid connection point active power fed into the DRU.

6. The reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power according to claim 5, characterized in that, Based on the current active power and voltage amplitude at the grid connection point fed into the DRU, the current DC voltage margin and reactive power demand at the current DRU grid connection point are calculated, including: Obtain the current valve-side AC line voltage and commutation reactance; Using the current grid-connected active power and current grid-connected voltage amplitude fed into the DRU as inputs, and DC current as an unknown variable, a steady-state interface model of the DRU converter is constructed. The steady-state interface model of the DRU converter is solved to obtain the current DC current; The current DC voltage margin is calculated based on the current DC current, the current AC line voltage on the valve side, and the commutation reactance. Based on the corrected active power at the current grid connection point boundary, the three-phase complex power at the current grid connection point is calculated. Take the imaginary part of the three-phase complex power at the current grid connection point to obtain the reactive power demand at the current DRU grid connection point.

7. A reactive power collaborative optimization device for a multi-terminal heterogeneous power collection system for offshore wind power, characterized in that, include: Data acquisition module and reactive power optimization and adjustment module; The data acquisition module is used to acquire bus data, branch data, generator data, and several candidate input combinations of AC filters for offshore wind power collection systems, and to construct an admittance matrix based on the bus data and branch data. The reactive power optimization and adjustment module is used to repeatedly perform reactive power optimization solution operations for each candidate input combination based on the current candidate input combination, generator data and admittance matrix to obtain the corresponding optimal reactive power optimization parameters and objective function value, and to perform reactive power optimization adjustment based on the candidate input combination and optimal reactive power optimization parameters corresponding to the minimum objective function value. The reactive power optimization solution operation includes: Obtain the current reactive power output of the wind turbine and the current voltage amplitude at the grid connection point; wherein, the initial reactive power output of the wind turbine is calculated based on the preset initial power factor, and the initial voltage amplitude at the grid connection point is calculated based on the preset grid connection point boundary voltage; Construct the coefficient matrix of the current AC power flow linear equation system based on the admittance matrix. Construct the right-hand vector of the current AC power flow linear equation system based on the active power output of the wind turbine, the current reactive power output of the wind turbine and the current voltage amplitude of the grid connection point in the generator data. Perform matrix solution on the current AC power flow linear equation system to obtain the current approximate voltage phasor of the non-grid connection point. Based on the active power output of the wind turbine, the current reactive power output of the wind turbine, the current voltage amplitude at the grid connection point, the admittance matrix, the current candidate input combination, and the current approximate voltage phasor, calculate and determine the current reactive power optimization parameters, the current objective function value, the current constraint violation, and the current solution convergence state. If the current solution convergence state is convergence, the current reactive power optimization parameters and the current objective function value are used as the optimal reactive power optimization parameters and objective function value corresponding to the current candidate input combination; otherwise, based on the current objective function value and the current constraint violation, the updated wind turbine reactive power output and grid connection point voltage amplitude are calculated.

8. The reactive power collaborative optimization device for a multi-terminal heterogeneous power collection system for offshore wind power according to claim 7, characterized in that, The reactive power optimization and adjustment module includes: The system includes a weight acquisition unit, an objective function construction unit, a constraint construction unit, a data calculation unit, an amplitude calculation unit, and a convergence judgment unit. The weight acquisition unit is used to acquire the reactive power penalty weight of the auxiliary MMC and the reactive power penalty weight of the wind turbine. The objective function construction unit is used to construct the objective function of a multi-source reactive power collaborative optimization model with the objectives of minimizing grid loss of the power collection system and maximizing the dynamic reactive power margin of the auxiliary MMC, based on the preset rated reactive power capacity of the auxiliary MMC, the reactive power penalty weight of the auxiliary MMC and the reactive power penalty weight of the wind turbine. The constraint construction unit is used to construct the constraint conditions of the multi-source reactive power collaborative optimization model based on the preset node voltage amplitude limit, the preset rated reactive power capacity of the auxiliary MMC, the preset branch apparent power rated capacity, and the preset wind turbine reactive power output limit. The data calculation unit is used to calculate and determine the current reactive power optimization parameters, the current objective function value, and the current constraint violation amount based on the objective function, constraints, active power output of the wind turbine, current reactive power output of the wind turbine, current grid connection point voltage amplitude, admittance matrix, current candidate input combination, and current approximate voltage phasor. The amplitude calculation unit is used to calculate the amplitude value of the change in the current optimization parameters and the amplitude value of the change in the current objective function based on the current reactive power optimization parameters, the current objective function value and the current constraint violation amount; The convergence judgment unit is used to determine if the current solution convergence state is converged if the change magnitude of the current optimization parameter, the change magnitude of the current objective function, and the current constraint violation do not exceed the corresponding preset threshold; otherwise, the current solution convergence state is non-convergent.

9. A terminal device, characterized in that, The system includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement a reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power as described in any one of claims 1 to 6.

10. A storage medium, characterized in that, The storage medium includes a stored computer program, wherein, when the computer program is running, it controls the device where the storage medium is located to execute a reactive power collaborative optimization method for a multi-terminal heterogeneous power collection system for offshore wind power as described in any one of claims 1 to 6.

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