A control parameter setting method of a grid-connection and tracking type wind farm combined system

Abstract

The application discloses a control parameter setting method of a grid-constructing and grid-following type wind farm parallel system, belongs to the technical field of power system stability analysis, and comprehensively considers a complex scene of the grid-constructing and grid-following type wind farm parallel connection. The grid-following type wind farm changes output through logical switching before and after a fault, a simplified model is established for the scene, a phase-locked loop part of the grid-following type wind farm is ignored, the grid-constructing type wind farm is simplified into a second-order nonlinear differential equation, and a simplified system large signal model is constructed. Through construction of the simplified large signal mathematical model of the grid-constructing and grid-following type wind farm two-machine parallel system, the grid-constructing type wind farm double-loop feedback control parameters are analyzed and set offline, the grid-constructing type wind farm can keep transient power angle stability, current limitation and meet the grid-connected standard of reactive current under typical voltage drop of the grid-constructing and grid-following type wind farm parallel system, the transient performance of the grid-constructing type wind farm after disturbance of the system is improved, and the safe and stable operation of the power grid is maintained.

Description

Technical Field

[0001] This invention belongs to the field of power system stability analysis technology, and more specifically, relates to a method for tuning control parameters of a grid-connected and grid-linked wind farm parallel system. Background Technology

[0002] Developing new energy sources, represented by wind power, is a major requirement for my country's clean energy transition. Grid connection of wind power is the primary means to achieve its economical, efficient, and large-scale consumption. Wind power connected to the grid via power electronic equipment has characteristics such as low inertia, weak disturbance rejection, and dynamic response across multiple time scales. However, wind power grid-connected systems may experience transient power angle stability problems dominated by the power electronic equipment.

[0003] Parallel operation of grid-connected and grid-connected wind farms is a typical scenario that future power systems will need to address. Grid-connected wind farms are essentially current-source controlled, capable of directly limiting fault current by modifying current reference values. However, grid-connected wind farms have significantly lower overcurrent capacity than grid-connected ones. To avoid physical damage to the converter, current limiting is another crucial issue for grid-connected converters. Simultaneously, current limiting also affects the transient power angle stability of grid-connected wind farms, requiring comprehensive consideration. Secondly, grid connection standards impose requirements on the reactive current output of wind turbines, especially under severe fault conditions, where it is difficult to balance current limits with reactive current support. Furthermore, parallel operation of grid-connected and grid-connected wind farms leads to mutual interactions, posing challenges to the analysis and tuning of the feasible region of control parameters.

[0004] Existing research on the control of grid-connected wind farms focuses only on transient power angle issues, with a few studies also considering current constraints, but neglecting the reactive current requirements of grid connection standards. Secondly, existing research often determines control parameter tuning based on small-disturbance stability, without addressing transient stability. This stems from the complexity of large-signal models and the lack of feasible domain analysis methods. Therefore, how to comprehensively consider both grid-connected and parallel-connected wind farms, establish a suitable simplified large-signal model, perform control parameter domain analysis, and simultaneously achieve multiple control objectives is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method for tuning control parameters of a parallel system of grid-connected and grid-following wind farms. The aim is to establish a suitable simplified large-signal model for the parallel system, analyze and tune control parameters to improve the transient performance of the grid-connected wind farm after disturbance, while simultaneously reducing the computational complexity of transient analysis and tuning. This solves the technical problem of the difficulty in analyzing the transient stability of grid-connected wind farms after disturbance.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for tuning control parameters of a parallel system of grid-connected and grid-following wind farms is provided, comprising:

[0007] S1: Construct a virtual synchronous control network-type wind farm structure, which includes a dual-loop feedback control structure to achieve transient power angle stabilization and current control;

[0008] S2: By using grid connection standards and output current limiting during faults, the grid-connected wind farm structure is reasonably simplified, and a large-signal mathematical model of the grid-connected and grid-connected wind farm parallel system is established in combination with the grid-connected wind farm structure.

[0009] S3: Traverse multiple control parameter combinations of the dual-loop feedback control structure within the range of power grid sag values, and use the control parameter combinations to solve the nonlinear differential equation of the large-signal mathematical model to obtain the state parameters of the grid-type wind field;

[0010] S4: Using the transient characteristics reflected by the state parameters of the grid-type wind farm, determine whether the combination of control parameters corresponding to the voltage drop range of each power grid meets the control objective, which involves the transient power angle stability region and the current limiting region;

[0011] S5: Select the combination of control parameters that meets the control objective and tune it.

[0012] In one embodiment, the nonlinear differential equation of the large-signal mathematical model is:

[0013]

[0014] Where J is the virtual inertia constant, D represents the damping coefficient, δ is the power angle, P0 is the reference value of the active power output of the grid-type wind farm, and P e For grid-type wind farms to output active power, U n Where k is the rated voltage, k1 is the feedback coefficient of the active power loop feedback control, E is the terminal voltage of the grid-type wind farm structure, and α is the impedance simplification coefficient R / (R 2 +X 2 ), U g Let θ be the grid voltage. vsg Let X be the phase angle, k2 be the feedback coefficient of the reactive power loop feedback control, and β be the impedance simplification coefficient. 2 +X 2 ), E(θ) vsg k2) represents the terminal voltage E and θ vsg The functional relationship between k and k2.

[0015] In one embodiment, the generator terminal voltage equation of the grid-type wind farm structure in the large-signal mathematical model is:

[0016]

[0017] U0 is the terminal voltage of the grid-connected wind turbine, U 0d For the d-axis component of the terminal voltage of the grid-type wind farm, a1 is the impedance ratio Z1 / (Z1+Z3), a3 is the impedance ratio Z3 / (Z1+Z3), E is the terminal voltage of the grid-type wind farm structure, and δ pll The phase difference δ between the phase angle of a grid-type wind farm and the phase angle at the turbine end of a follow-grid wind farm. pll =θ vsg -θ pll θ pll To match the phase angle of the turbine end in the grid-type wind farm, I 2d To match the amplitude of the active current output by the grid-type wind farm, I 2q To measure the amplitude of the reactive current output by the grid-connected wind farm, R3 is the resistance of the line from the common coupling point to the grid, X3 is the reactance of the line from the common coupling point to the grid, X2 is the reactance of the line from the grid-connected wind farm to the common coupling point, and R2 is the resistance of the line from the grid-connected wind farm to the common coupling point. U 0q To correspond to the q-axis component of the terminal voltage of the grid-type wind farm, the impedance of the line from the grid-type wind farm to the common coupling point is Z1 = R1 + jX1, the impedance of the line from the grid-type wind farm to the common coupling point is Z2 = R2 + jX2, and the impedance of the line from the common coupling point to the power grid is Z3 = R3 + jX3.

[0018] In one embodiment, the large-signal mathematical model includes the following relationship between the turbine terminal voltage and the common coupling point voltage of the grid-connected wind farm structure:

[0019]

[0020] Among them, U pcc For the voltage at the common coupling point, δ pcc To virtually synchronize the control of the phase difference between the wind field and the common coupling point, U pll To collect voltage at the network-type terminal.

[0021] In one embodiment, the simplified control switching logic for the grid-type wind farm in S2 is as follows:

[0022] When the system is in normal operation, the current reference value control switch S switches to logic 0, and the active current reference value I... 2dref Set as rated current, reactive current reference value I 2qref =0;

[0023] When a grid fault occurs, the switch will switch to logic 1, which is set due to both grid connection standards and the requirement to limit the output current amplitude during a fault. 2qref It is 1.2 pu, while I 2dref It is 0.

[0024] In one embodiment, the control objective in S4 includes three feasible parameter domains;

[0025] Region 1: Transient work angle stable region;

[0026] Region 2: Transient power angle stability and current limiting region;

[0027] Region 3: Region where reactive current output meets the standard and simultaneously satisfies the two objectives mentioned above.

[0028] According to another aspect of the present invention, a control parameter tuning device is provided for a parallel system of grid-connected and grid-following wind farms, comprising:

[0029] A construction module is used to construct a virtual synchronous control network-type wind farm structure, which includes a dual-loop feedback control structure to achieve transient power angle stabilization and current control.

[0030] A module is established to utilize the common requirements of grid connection standards and output current limiting during faults for the grid-connected wind farm structure, and in conjunction with the grid-connected wind farm structure, to establish a large-signal mathematical model of the parallel system of the grid-connected and grid-connected wind farms.

[0031] The solution module is used to traverse multiple control parameter combinations of the dual-loop feedback control structure within the range of power grid sag values, and use the control parameter combinations to solve the nonlinear differential equation of the large-signal mathematical model to obtain the state parameters of the grid-type wind field.

[0032] The judgment module is used to determine whether the combination of control parameters corresponding to the voltage drop range of each power grid meets the control target by using the transient characteristics reflected by the state parameters of the grid-type wind farm. The control target involves the transient angle of attack stability region and the current limiting region.

[0033] The tuning module is used to select and tune the combination of control parameters that meet the control objective.

[0034] According to another aspect of the present invention, a parallel system for grid-connected and grid-following wind farms is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described method.

[0035] According to another aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0036] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0037] (1) The control parameter tuning method for the parallel system of grid-connected and grid-connected wind farms provided by the present invention comprehensively considers the complex scenario of parallel connection of grid-connected and grid-connected wind farms. Before and after the fault, the output of the grid-connected wind farm changes through logic switching. The scenario is simplified and modeled, ignoring the phase-locked loop of the grid-connected wind farm, and the grid-connected wind farm is simplified to a second-order nonlinear differential equation, and a simplified system large-signal model is constructed. By constructing a simplified large-signal mathematical model of the parallel system of grid-connected and grid-connected wind farms, the dual-loop feedback control parameters of the grid-connected wind farm are analyzed and tuned in the offline stage. This enables the grid-connected wind farm to maintain transient power angle stability, current limitation and reactive current meeting grid connection standards under typical voltage drop in the parallel system with the grid-connected wind farm, thereby improving the transient performance of the grid-connected wind farm after the system is disturbed and maintaining the safe and stable operation of the power grid.

[0038] (2) The simplified large-signal mathematical model of the two-machine parallel system in this scheme adopts dual-loop feedback control regulation, so that the grid-type wind farm can simultaneously take into account transient power angle stability, current limitation and grid connection standard requirements for output reactive current when the voltage drops during system faults, thereby improving the transient performance of the system.

[0039] (3) This scheme divides the feasible regions of three parameters for transient stability: the transient power angle stability region, the transient power angle stability and current limiting region, and the region where the reactive current output meets the standard and simultaneously satisfies the above two objectives. Visualizing the feasible range of control parameters to achieve multiple control objectives provides a basis for tuning the dual-loop control parameters. Attached Figure Description

[0040] Figure 1 This is a framework diagram of the control parameter tuning method for a parallel system of grid-connected and grid-following wind farms provided in an embodiment of the present invention;

[0041] Figure 2 The topology and control structure diagram of the parallel system of grid-connected and grid-following wind farms provided in the embodiments of the present invention;

[0042] Figure 3a , Figure 3b and Figure 3c A three-dimensional parameter feasible region analysis diagram for a grid voltage drop to 0.3 pu provided in an embodiment of the present invention;

[0043] Figure 4a , Figure 4b , Figure 4c and Figure 4d This invention provides a parameter feasibility domain analysis under operating conditions for embodiments of the present invention.

[0044] Figure 5a and Figure 5b This is an analysis diagram of the transient three-dimensional phase trajectory under different control parameters provided in the embodiments of the present invention;

[0045] Figure 6a , Figure 6b , Figure 6c and Figure 6d The diagram shows the dynamic response during a transient process under different control parameters, as provided in the embodiments of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0047] like Figure 1 As shown, the control parameter tuning method for a parallel system of grid-connected and grid-following wind farms provided by the present invention includes the following steps:

[0048] S1, construct a virtual synchronous control network-type wind farm, and add a dual-loop feedback control structure to simultaneously achieve transient power angle stabilization and current control;

[0049] Specifically, the topology and control structure of the parallel system of grid-connected and grid-following wind farms are as follows: Figure 2 As shown, grid-type wind farms and parallel-grid type wind farms are connected to a common coupling point via transformers and parallel double-circuit transmission lines, and then connected to the grid via these lines. Z1, Z T L f C f With Z2, Z T2 L f2 C f2 These represent the line impedance, transformer impedance, filter inductance, and capacitor, respectively, for a virtual synchronous control wind farm and a grid-connected wind farm. The terminal voltage of a grid-connected wind farm is represented as U0∠θ. pll The output current is expressed as Current phase angle is I 2d I 2q These represent the active and reactive current amplitudes, respectively. The terminal voltage of the wind turbine in the virtual synchronous control wind farm is expressed as E∠θ. vsg Similarly, the output current is expressed as Let its current phase angle be denoted as U. The voltage at the point of common coupling is expressed as U. pcc ∠θ pcc The grid voltage is represented as U. g ∠θ g Z3 is the impedance of the grid-connected line, with a unit resistance of r1 = 0.2542 Ω / km and a unit reactance of l1 = 2.287 e. -3 H / km. k1 and k2 are the feedback coefficients of the feedback control in the active and reactive power loops, respectively. Iq I q0 These are the output reactive current and the reactive current setpoint, respectively. The parameters of the parallel system for grid-connected and grid-connected wind farms are shown in Table 1.

[0050] Table 1 Parameters of Parallel Systems for Grid-Connected and Networked Wind Farms

[0051] <![CDATA[P1 / P2]]> 100MW <![CDATA[U g ]]> 110kV <![CDATA[Q1 / Q2]]> 0 / 0MW <![CDATA[Z T1 / WITH T2 ]]> 0.005 / 0.005pu J 0.3pu <![CDATA[L f1 / L f2 ]]> 0.2pu D 2pu <![CDATA[C f1 / C f2 ]]> 0.15pu <![CDATA[K q ]]> 0.2pu <![CDATA[Length of Z1]]> 30km E 690V <![CDATA[Length of Z2]]> 20km <![CDATA[U0]]> 690V <![CDATA[Length of Z3]]> 10km

[0052] S2. Based on the control structure of the grid-type wind farm under study, and combined with the common requirements of grid connection standards and output current amplitude limits during faults for grid-type wind farms, a simplified large-signal mathematical model of the parallel system of two wind farms in grid-type and grid-type wind farms is established.

[0053] Specifically, in the simplified large-signal mathematical model of the two-machine parallel system, the nonlinear differential equation of the grid-type wind field after considering dual-loop feedback control is as follows:

[0054]

[0055] Where, E(θ) vsg k2) represents the terminal voltage E and θ vsg The functional relationship between k and k2.

[0056] For grid-type wind farms, neglecting the transient effects of phase-locked loop control, the expansion of the turbine terminal voltage equation is as follows:

[0057]

[0058] In the formula, δ pll =θ vsg -θ pll The line impedances are Z2 = R2 + jX2 and Z3 = R3 + jX3.

[0059] The relationships between the terminal voltage of the wind turbine and the voltage at the common coupling point in a grid-type wind farm are as follows:

[0060]

[0061] In the formula, δ pcc =θ vsg -θ pcc This represents the phase difference between the virtual synchronous control wind field and the common coupling point.

[0062] The control switch logic for a grid-type wind farm can be described as follows: When the system is in normal condition, the current reference value control switch S switches to logic 0, and the active current reference value I... 2dref Set as rated current, reactive current reference value I 2qrefThe value is 0; when a grid fault occurs, the switch will switch to logic 1, which is set due to the combined requirements of grid connection standards and the limitation of output current amplitude during faults. 2qref It is 1.2 pu, while I 2dref It is 0.

[0063] S3, based on the typical range of power grid drop, solve the nonlinear differential equation using a fast solution method, and traverse all control parameter combinations of the dual-loop feedback control of the grid-type wind farm within the range of values;

[0064] Specifically, when the grid voltage drops to the range of 0.1 to 0.5 pu, the control effect of different combinations of k1 and k2 is tested. k1 and k2 are taken from the range of 0 to 3 pu in steps of 0.01 pu. The nonlinear differential equation is solved quickly by calling the "ode45" solution method in Matlab.

[0065] S4. Based on the transient characteristics of the grid-type wind field, determine whether each pair of control parameter combinations meets the control objective, and divide the parameter domain into three parameter feasible domains.

[0066] Specifically, such as Figure 4a , Figure 4b , Figure 4c and Figure 4d As shown, the three feasible regions for the control parameter combination are: the transient power angle stability region, the transient power angle stability and current limiting region, and the region where the reactive current output meets the standard and simultaneously meets the above two objectives.

[0067] S5 adjusts the dual-loop feedback control parameters of the grid-type wind farm based on the preset voltage drop.

[0068] Specifically, the voltage drop caused by the most common fault in the preset system is 0.1 pu. Therefore, a suitable combination of dual-loop feedback control parameters can be selected from the feasible parameter domain three to tune the controller to cope with system faults. In this embodiment, the tuning control parameters are k1 = 1.5 and k2 = 0.4. It should be noted that the preset voltage drop level and thus the tuning parameters are determined by the actual situation of the application system, but this does not affect the feasibility of the method.

[0069] like Figure 3a , Figure 3b and Figure 3c As shown, in a two-unit parallel system, to study the impact of the output current during a fault on the transient power angle stability of the virtual synchronous control wind farm, the ratio of the active current to the reactive current amplitude can be set as parameter k3 = I. 2d / I 2qThe value range is 0 to +∞. Since a new parameter k3, characterizing the output current of the grid-type wind farm, is introduced, the feasible region of the parameter is a 3D plot. Due to the long computer traversal time, to find the pattern, we first take a grid voltage drop to 0.3 pu as an example and plot the feasible region of the parameter combination of k1, k2, and k3. We observe that as k3 increases from small to large, Figure 3a , Figure 3b and Figure 3c The cross-sectional areas of the three regions shown gradually decrease. The conclusion is that, under amplitude constraints, the more the output current of a grid-connected wind farm leans towards active power, the less conducive it is to achieving the goals of transient power angle stability, current limiting, and grid connection standards for virtual synchronous control of the wind farm. The best effect is achieved when k3 = 0, i.e., when the grid-connected wind farm outputs purely reactive current. Furthermore, it can be seen that the influence of k3 is far less than that of k1 and k2, and the three-dimensional diagram is not conducive to observing the internal situation. Therefore, k3 = 0 is directly selected as the operating condition, i.e., the output current of the grid-connected wind farm is directly considered to be purely reactive.

[0070] like Figure 4a , Figure 4b , Figure 4c and Figure 4d As shown, under the condition of pure reactive current output in a grid-connected wind farm, the feasible regions of parameters were tested when the grid voltage dropped to four fault levels of 0.1 to 0.4 pu. It can be seen that among the feedback parameters of the dual-loop control, a larger k2 is beneficial for limiting current but not for transient power angle stability, while a larger k1 can enhance transient power angle stability while limiting active current. The three feasible regions of the control parameter combination are: (1) transient power angle stability region; (2) transient power angle stability and current limiting region; (3) region where reactive current output meets the standard and simultaneously meets the above two objectives. By flexibly combining k1 and k2, the transient power angle stability, current limiting and reactive current output required by the grid connection standard can be achieved simultaneously.

[0071] Taking the case where the grid voltage drops to 0.1 pu as an example, to more intuitively and graphically depict the impact of each set of parameters on the system's transient characteristics, the phase trajectory diagram method is used for analysis. For example... Figure 5a As shown, when parameters (k1=0, k2=0) are selected, the phase angle diverges and becomes unstable after the fault, and the output current also exceeds the current limit of 1.2 pu, indicating that the parameters do not meet the control objective. In contrast, as Figure 5b As shown, when the parameters (k1 = 1.5, k2 = 0.4) are selected, the phase angle converges and stabilizes after the fault, and the output current does not exceed the current limit of 1.2 pu, indicating that the set of parameters meets the control objective.

[0072] Time-domain simulation was performed to verify the four sets of dual-loop feedback control parameters. For example... Figure 6aAs shown, the parameters are set to (k1=0, k2=0), indicating that the dual-loop feedback control is not in use, the virtual synchronous control causes transient power angle instability in the wind farm, and the current also exceeds the limit. Figure 6b As shown, with parameters set to (k1 = 1.5, k2 = 0), although the transient power angle did not become unstable, the current exceeded the limit. Figure 6c As shown, with parameters set to (k1 = 1.2, k2 = 1), the transient power angle is stable and the current does not exceed the limit. However, the current is below 1.0 pu, which prevents the reactive current from meeting the grid connection standard. Figure 6d As shown, with parameters set (k1 = 1.5, k2 = 0.4), the transient power angle is stable, the current does not exceed the limit, and the reactive current is equal to 1.0 pu, meeting the grid connection standard. In summary, according to... Figure 6a , Figure 6b , Figure 6c and Figure 6d The simulation results can verify Figure 4a The control objectives that can be achieved in each region also verify that the analysis based on the feasible region of parameters can be used to tune the dual-loop feedback parameters.

[0073] This invention provides a method for tuning control parameters in a parallel system of grid-connected and grid-connected wind farms. This method can construct a simplified large-signal mathematical model of the parallel system of two wind farms connected to the grid, and analyze and tune the dual-loop feedback control parameters of the grid-connected wind farm in the offline stage. This enables the grid-connected wind farm to maintain transient power angle stability, current limitation, and reactive current compliance with grid connection standards under typical voltage dips in the parallel system with the grid-connected wind farm. This improves the transient performance of the grid-connected wind farm after system disturbance and maintains the safe and stable operation of the power grid.

[0074] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for tuning control parameters of a parallel system of grid-connected and grid-following wind farms, characterized in that, include: S1: Construct a virtual synchronous control network-type wind farm structure, which includes a dual-loop feedback control structure to achieve transient power angle stabilization and current control; S2: By using grid connection standards and output current limiting during faults, the grid-connected wind farm structure is reasonably simplified. Combined with the grid-connected wind farm structure, a large-signal mathematical model of the grid-connected and grid-connected wind farm parallel system is established. S3: Traverse multiple control parameter combinations of the dual-loop feedback control structure within the range of power grid sag values, and use the control parameter combinations to solve the nonlinear differential equation of the large-signal mathematical model to obtain the state parameters of the grid-type wind field; S4: Using the transient characteristics reflected by the state parameters of the grid-type wind farm, determine whether the combination of control parameters corresponding to the voltage drop range of each power grid meets the control objective, which involves transient power angle stability and current limitation; S5: Select a combination of control parameters that meets the control objective and perform tuning; The generator terminal voltage equation for the grid-type wind farm structure in the large-signal mathematical model is as follows: U 0 represents the terminal voltage of the grid-connected wind turbine. U 0d To match the terminal voltage of the grid-type wind farm d Axial components, a 1 represents the impedance ratio Z 1 / ( Z 1+ Z 3), a 3 represents the impedance ratio Z 3 / ( Z 1+ Z 3), The terminal voltage of the grid-type wind farm structure. δ pll Phase angle of the grid-type wind field θ vsg Phase angle with the turbine end of the grid-type wind farm θ pll phase difference δ pll =θ vsg -θ pll , This is the grid voltage. I 2d To match the amplitude of the active current output by the grid-type wind farm, I 2q To match the amplitude of the reactive current output by the grid-type wind farm, R 3 represents the resistance from the point of common coupling to the power grid line. X 3 represents the reactance of the line from the point of common coupling to the power grid. X 2 represents the reactance of the line from the grid-type wind farm to the common coupling point. R 2 represents the resistance of the line from the grid-type wind farm to the common coupling point. U 0q To match the terminal voltage of the grid-type wind farm q Axial component, impedance of the line from the network-type wind farm to the common coupling point Z 1 is R 1+j X 1, R 1 and X 1 represents the resistance and reactance of the line from the grid-type wind farm to the common coupling point, and the impedance of the line from the grid-type wind farm to the common coupling point. Z 2= R 2+j X 2. Impedance from the point of common coupling to the power grid line Z 3= R 3+j X 3; The relationship between the generator terminal voltage and the common coupling point voltage of the grid-type wind farm structure included in the large-signal mathematical model is as follows: in, U pcc For the voltage at the common coupling point, δ pcc To achieve virtual synchronization control of the phase difference between the wind field and the common coupling point, U pll To collect voltage at the network-connected terminal; The control objective in S4 includes three feasible parameter domains; Region 1: Transient work angle stable region; Region 2: Transient power angle stability and current limiting region; Region 3: Region where reactive current output meets the standard and simultaneously satisfies the two objectives mentioned above.

2. The control parameter tuning method for the parallel system of grid-connected and grid-following wind farms as described in claim 1, characterized in that, The nonlinear differential equation of the large-signal mathematical model is: ； in, J For virtual inertia constant, D Represents the damping coefficient. For the angle of attack, This serves as a reference value for the output active power of a grid-type wind farm. To output active power for grid-type wind farms Rated voltage, For active power loop feedback control, the feedback coefficient is... The terminal voltage of the grid-type wind farm structure. impedance simplification coefficient R / ( R 2 + X 2 ), This is the grid voltage. For the phase angle of the grid-type wind field, For reactive power loop feedback control, (This refers to the feedback coefficient.) impedance simplification coefficient X / ( R 2 + X 2 ), E ( θ vsg , k 2) Terminal voltage E and θ vsg , k The functional relationship of 2.

3. The control parameter tuning method for a parallel system of grid-connected and grid-following wind farms as described in claim 1 or 2, characterized in that, The simplified control switch logic for the grid-type wind farm in S2 is as follows: When the system is in normal operation, the current reference value control switch S Switch to logic 0, active current reference value I 2dref Set as rated current, reactive current reference value I 2qref =0; When a grid fault occurs, the switch will switch to logic 1, due to both grid connection standards and the requirement to limit the output current amplitude during a fault. I 2qref It is 1.2 pu, while I 2dref It is 0.

4. A control parameter tuning device for a parallel system of grid-connected and grid-following wind farms, characterized in that, A method for tuning control parameters for executing the parallel system of grid-connected and grid-following wind farms as described in any one of claims 1-3, comprising: A construction module is used to construct a virtual synchronous control network-type wind farm structure, which includes a dual-loop feedback control structure to achieve transient power angle stabilization and current control. A module is established to reasonably simplify the grid-connected wind farm structure by utilizing grid connection standards and output current limiting during faults, and to establish a large-signal mathematical model of the grid-connected and grid-connected wind farm parallel system in combination with the grid-connected wind farm structure. The solution module is used to traverse multiple control parameter combinations of the dual-loop feedback control structure within the range of power grid sag values, and use the control parameter combinations to solve the nonlinear differential equation of the large-signal mathematical model to obtain the state parameters of the grid-type wind field. The judgment module is used to determine whether the combination of control parameters corresponding to each power grid drop value range meets the control target by using the transient characteristics reflected by the state parameters of the grid-type wind farm. The control target involves transient power angle stability and current limitation. The tuning module is used to select and tune the combination of control parameters that meet the control objective.

5. A parallel system for grid-connected and grid-following wind farms, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 3.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 3.

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