Wind power grid-connected system impedance modeling method and device considering wind power active output, equipment and medium

Abstract

The invention relates to the technical field of wind power grid-connected operation control, in particular to a wind power grid-connected system impedance modeling method and device considering wind power active output, equipment and a medium, and the method comprises the steps: building a machine side model of a direct drive fan, building a grid side small disturbance dynamic model of the direct drive fan, and building a grid side initial impedance model; on the basis of the initial impedance model of the grid side, taking the active power output of the fan as an independent variable, perfecting an impedance model, and establishing a wind power grid-connected system impedance model containing a fan output level influence factor; calculating the equivalent impedance of the wind power grid-connected system under different active power output conditions, and evaluating the stability of the system under different active power output conditions; the difference of the output of each fan is considered into the stability analysis of the wind power grid-connected system, so that the active output is used as an independent variable to directly influence an impedance model of the wind power grid-connected system, and modeling support is provided for the influence research and mechanism analysis of parameters such as the wind power active output on the stability of the grid-connected system.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power grid-connected operation control, and in particular to a method, device, equipment and medium for modeling impedance of a wind power grid-connected system taking into account active output of wind power. Background Art

[0002] In recent years, my country's wind power industry has developed rapidly and has become an important force in promoting the transformation of the energy structure. According to data from the National Energy Administration, as of the first half of 2024, the country's new wind power grid-connected capacity reached 25.84 million kilowatts, a year-on-year increase of 12%, and the cumulative grid-connected capacity exceeded 467 million kilowatts, a year-on-year increase of 20%. These data not only show the key position of wind power in my country's energy structure, but also indicate the huge potential of the wind power industry in the future. In terms of power generation, the country's wind power generation reached 508.8 billion kilowatt-hours in the first half of 2024, a year-on-year increase of 10%. The proportion of wind power in the country's total power generation continues to rise, and it has become the second largest source of electricity after thermal power. Wind power, with its clean and renewable characteristics, provides important support for achieving the "dual carbon" goal.

[0003] However, in large-scale wind farms, due to differences in wind turbine locations and wind speeds, the operation modes of wind turbines are not uniform, which leads to inconsistent active output of each wind turbine. During the operation of the wind farm, changes in active output have a significant impact on the stability of the grid-connected system. When the active output changes, the initial values ​​of the system's state variables change accordingly, which in turn affects the interaction of each system link. Therefore, studying the impact of active output on the stability of the grid-connected system is of great significance to improving the overall stability of the system.

[0004] Although the existing direct-drive wind turbine grid-connected system modeling can analyze the impact of active output on system stability to a certain extent, it has shortcomings in the following aspects: first, the existing model cannot effectively quantify the specific impact of active output on system stability; second, the existing model lacks intuitive and clear model support when analyzing the mechanism of wind turbine output on the stability of the grid-connected system. Therefore, the current wind power grid-connected system impedance modeling method cannot fully and accurately reflect the impact of the dynamic changes of wind power active output on system stability. Therefore, it is necessary to establish a wind power grid-connected system impedance modeling method that takes into account the impact of wind power active output to better support system stability analysis and optimization control.

[0005] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0006] The present invention provides a method, device, equipment and medium for modeling impedance of a wind power grid-connected system taking into account the active output of wind power, thereby effectively solving the problems in the background technology.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: a wind power grid-connected system impedance modeling method considering the active output of wind power, comprising the following steps:

[0008] S10: establishing a machine-side model of the direct-drive wind turbine, wherein the machine-side model is based on the machine-side topological structure and control link of the direct-drive wind turbine, adopts a dq rotating coordinate system, and sets the d-axis along the magnetic flux direction of the permanent magnet of the direct-drive generator;

[0009] S20: Based on the machine-side model, a small disturbance dynamic model of the direct-drive wind turbine is established. The small disturbance dynamic model of the direct-drive wind turbine is based on the grid-side topology and control link. The control link includes a voltage outer loop control model and a current inner loop control model, and considers the small disturbance effect of the phase-locked loop on the grid connection point voltage.

[0010] S30: connecting the machine side and the grid side through a back-to-back DC link, treating the output power of the machine side converter as equivalent to a constant power source, ignoring the influence of the machine side dynamics on the small disturbance dynamic model of the grid side, and constructing an initial impedance model of the grid side;

[0011] S40: Based on the initial impedance model of the grid side, taking the active output of the wind turbine as an independent variable, an impedance model of the wind power grid-connected system including factors affecting the output level of the wind turbine is established;

[0012] S50: Based on the wind power grid-connected system impedance model, the equivalent impedance of the wind power grid-connected system under different active output conditions is calculated, and the stability of the system under different active output conditions is evaluated.

[0013] Further, in step S20, the current inner loop control model of the grid-side converter includes:

[0014]

[0015] Where U cd , U cq are the d-axis and q-axis components of the grid-side converter output voltage, respectively. c (s) is the current inner loop transfer function, I cdref ,I cqref are the d-axis and q-axis components of the grid-side converter output current reference value, I cd ,I cq are the d-axis and q-axis components of the grid-side converter output current, ω1 is the fundamental angular frequency, L g It is the grid-side filter inductor.

[0016] Furthermore, in step S20, the voltage outer loop control model includes:

[0017]

[0018] In the formula, I cdref ,I cqref are the d-axis and q-axis components of the grid-side converter output current reference value, U dc is the DC side voltage, U dcref is the DC side voltage reference value, H u (s) is the transfer function of the voltage outer loop.

[0019] Furthermore, in step S20, the control model considering the influence of small disturbance of the phase-locked loop on the grid connection point voltage includes:

[0020]

[0021] In the formula, ω pll is the phase-locked loop output angular frequency, H pll (s) is the phase-locked loop transfer function, u q is the q-axis component of the grid-side converter output voltage after the filter, θ pll is the phase-locked loop output phase angle, s is the differential symbol d / dt, k p , k i They are the proportional and integral control parameters of the phase-locked loop PI controller respectively.

[0022] Further, in step S20, the grid-side small disturbance dynamic model, by describing the small signal relationship model between the voltage and current of the grid-side converter in the dq rotating coordinate system under consideration of small disturbance, includes:

[0023]

[0024] Among them, Δu dq is the voltage dq axis small signal component of the grid-side converter after filtering, Δu cdq is the dq-axis small signal component of the grid-side converter output voltage, Δi cdqref is the dq-axis small signal component of the grid-side converter output current reference value, Δi cdq is the small signal component of the dq axis output current of the grid-side converter, G c is the current inner loop transfer function, G l is the transfer function of the filter link, G o is the coupling impedance transfer function.

[0025] Further, in step S20, the grid-side small disturbance dynamic model, considering the small disturbance impact model of the phase-locked loop on the grid connection point voltage, includes:

[0026]

[0027] In the formula, are the transfer functions that characterize the influence of small disturbance of the phase-locked loop on the voltage and current of the grid-side generator, G c is the current inner loop transfer function, G o is the coupling impedance transfer function, Respectively represent the dq-axis small signal components of the grid-side converter output voltage and current in the system coordinate system.

[0028] Further, in step S30, the small signal model of the DC link voltage obtained by connecting the machine side and the grid side through the back-to-back DC link and the topological structure of the DC link and the active power transmission relationship includes:

[0029]

[0030] Where U cd , U cq are the d-axis and q-axis components of the grid-side converter output voltage, I cd ,I cq are the d-axis and q-axis components of the grid-side converter output current, I dc is the back-to-back DC link output current, U dc is the voltage of capacitor C1 in the DC link.

[0031] Further, in step S30, the small signal model of the current loop reference value is obtained by connecting the machine side and the grid side through the back-to-back DC link, including:

[0032] Δi cdqref =G uw G w (G vi Δi cdq +G vu Δu cdq );

[0033] In the formula, G w To characterize the influence factor of output level on wind turbine impedance, G vi is the DC link current small signal transfer function, G vu is the DC link voltage small signal transfer function, Δu cdq is the dq-axis small signal component of the grid-side converter output voltage, Δi cdq It is the small signal component of the dq axis output current of the grid-side converter.

[0034] Furthermore, in step S40, the wind power grid-connected system impedance model including the wind turbine output level influencing factors is established, and the model of the wind turbine output level influencing factors includes:

[0035]

[0036] In the formula, G w To characterize the influence factor of output level on wind turbine impedance, P dc is the equivalent output power on the machine side, U dc is the voltage of capacitor C1 in the DC link, C1 is the capacitance in the back-to-back link, and s is the differential symbol d / dt.

[0037] Further, in step S40, based on the initial impedance model of the grid side, the wind turbine active output is used as an independent variable to establish a wind power grid-connected system impedance model including factors affecting the wind turbine output level. The direct-drive wind turbine's own equivalent impedance is defined as the ratio of voltage to current. The wind power grid-connected system impedance model includes:

[0038]

[0039] In the formula, Z pmsg is the impedance model of wind power grid-connected system, Δu cdq is the dq-axis small signal component of the grid-side converter output voltage, Δi cdq is the small signal component of the dq axis output current of the grid-side converter, G c is the current inner loop transfer function, G uw is the voltage outer loop transfer function, G o is the coupling impedance transfer function, are the transfer functions that characterize the influence of small disturbance of the phase-locked loop on the voltage and current of the grid-side generator, G w To characterize the influence factor of output level on wind turbine impedance, G vi is the DC link current small signal transfer function, G vu is the small signal transfer function of the DC link voltage.

[0040] The present invention also includes a wind power grid-connected system impedance modeling device taking into account the active output of wind power, using the above method, including:

[0041] A machine-side model building unit is used to build a machine-side model of the direct-drive wind turbine, wherein the machine-side model is based on the machine-side topological structure and control link of the direct-drive wind turbine, adopts a dq rotating coordinate system, and sets the d-axis along the magnetic flux direction of the permanent magnet of the direct-drive generator;

[0042] A grid-side small disturbance dynamic model establishment unit is used to establish a grid-side small disturbance dynamic model of the direct-drive wind turbine based on the machine-side model, wherein the grid-side small disturbance dynamic model is based on the grid-side topology and control links, wherein the control links include a voltage outer loop control model and a current inner loop control model, and consider the small disturbance effect of the phase-locked loop on the grid connection point voltage;

[0043] A grid-side initial impedance model building unit is used to connect the machine side and the grid side through a back-to-back DC link, to treat the output power of the machine-side converter as a constant power source, to ignore the influence of the machine-side dynamics on the small disturbance dynamic model of the grid side, and to build an initial impedance model of the grid side;

[0044] A wind turbine output level impedance model improvement unit is used to establish a wind power grid-connected system impedance model including wind turbine output level influencing factors based on the initial impedance model of the grid side and taking the wind turbine active output as an independent variable;

[0045] The system stability evaluation unit is used to calculate the equivalent impedance of the wind power grid-connected system under different active output conditions based on the wind power grid-connected system impedance model, and evaluate the stability of the system under different active output conditions.

[0046] The present invention also includes a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method described above is implemented.

[0047] The present invention also includes a storage medium on which a computer program is stored. When the computer program is executed by a processor, the method described above is implemented.

[0048] The beneficial effects of the present invention are:

[0049] The difference in output of each wind turbine is taken into account in the stability analysis of the wind power grid-connected system, so that the active output directly affects the impedance model of the wind power grid-connected system as an independent variable, providing modeling support for the study and mechanism analysis of the impact of wind power active output and other parameters on the stability of the grid-connected system.

[0050] By introducing active output as an independent variable, the impedance model is improved, which can directly analyze the impact of active output on system stability at a quantitative level, making system design and optimization control more accurate, and solving the problem that the existing model cannot clearly quantify the impact of wind power active output. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 A flow chart of the impedance modeling method for wind power grid-connected system considering the active output of wind power;

[0053] Figure 2It is a schematic diagram of the structure and control link of the direct-drive wind power grid-connected system;

[0054] Figure 3 It is the equivalent circuit diagram of the main circuit on the machine side;

[0055] Figure 4 Ignore the side dynamic equivalent grid-connected structure and control structure diagram for direct-drive wind turbines;

[0056] Figure 5 This is the topology diagram of the back-to-back links in a direct-drive wind turbine;

[0057] Figure 6 It is the principle diagram of phase-locked loop;

[0058] Figure 7 A schematic diagram of the structure of a wind power grid-connected system impedance modeling device considering the active output of wind power;

[0059] Figure 8 A schematic diagram of the structure of a computer device. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0061] like Figure 1 As shown: A wind power grid-connected system impedance modeling method considering wind power active output includes the following steps:

[0062] S10: establishing a machine-side model of the direct-drive wind turbine, the machine-side model is based on the machine-side topological structure and control link of the direct-drive wind turbine, adopts a dq rotating coordinate system, and sets the d-axis along the magnetic flux direction of the permanent magnet of the direct-drive generator;

[0063] S20: Based on the machine-side model, a small disturbance dynamic model of the direct-drive wind turbine is established. The small disturbance dynamic model of the grid side is based on the grid-side topology and control link. The control link includes a voltage outer loop control model and a current inner loop control model, and considers the small disturbance effect of the phase-locked loop (PLL) on the grid-connected point voltage.

[0064] S30: connecting the generator side and the grid side through a back-to-back DC link, treating the output power of the generator side converter as equivalent to a constant power source, ignoring the influence of the generator side dynamics on the small disturbance dynamic model of the grid side, and constructing an initial impedance model of the grid side;

[0065] S40: Based on the initial impedance model on the grid side, the wind turbine active output is taken as the independent variable, the impedance model is improved, and a wind power grid-connected system impedance model including the factors affecting the wind turbine output level is established;

[0066] S50: Based on the wind power grid-connected system impedance model, calculate the equivalent impedance of the wind power grid-connected system under different active output conditions, and evaluate the stability of the system under different active output conditions.

[0067] The difference in output of each wind turbine is taken into account in the stability analysis of the wind power grid-connected system, so that the active output directly affects the impedance model of the wind power grid-connected system as an independent variable, providing modeling support for the study and mechanism analysis of the impact of wind power active output and other parameters on the stability of the grid-connected system.

[0068] Although the model of the direct-drive wind turbine grid-connected system in the existing technology can analyze the impact of active output on system stability, it cannot quantify this impact. By introducing active output as an independent variable, the impedance model is improved, and the impact of active output on system stability can be directly analyzed at a quantitative level, making system design and optimization control more accurate, and solving the problem that the existing model cannot clearly quantify the impact of wind power active output.

[0069] When constructing the wind power grid-connected system model, this technical solution takes into account the independent establishment and association of the machine-side and grid-side models. In particular, through the small disturbance dynamic model and the impedance model, the influence of the control links (such as the voltage outer loop and the current inner loop) on the system stability is analyzed in detail. Combined with the influence of the phase-locked loop (PLL) on the grid connection point voltage, the accuracy of the system analysis is further improved. This comprehensive analysis method helps to more accurately reflect the dynamic characteristics of the wind power grid-connected system under different active output conditions.

[0070] By constructing an impedance model that includes factors affecting wind turbine output levels, this technical solution can calculate the equivalent impedance of the wind power system under different active output conditions and evaluate the stability of the system under different circumstances. This provides a theoretical basis for improving the grid-connected adaptability and safety of wind farms, enabling the system to more flexibly respond to the risks of system instability caused by fluctuations in wind turbine output.

[0071] The output power of the machine-side converter is equivalent to a constant power source through a back-to-back DC link, and the influence of the machine-side dynamics on the small disturbance model on the grid side is ignored. This simplified processing not only reduces the complexity of the model calculation, but also provides a rapid response capability for the real-time control of the wind power grid-connected system, enabling the system to adjust the active output changes more efficiently in actual operation.

[0072] Through a perfect impedance model, it can better support system stability analysis and optimization control, and provide a more intuitive and accurate analysis tool. This provides modeling support for the optimal design, scheduling and control strategies of future wind power systems and has important engineering application value.

[0073] by Figure 2The direct-drive wind power grid-connected system shown is the analysis object, and the schematic diagram of the machine-side converter topology structure is shown. Based on its topology structure and control link, a model of the wind power grid-connected system in the dq rotating coordinate system is established.

[0074] Among them, in step S10, the machine-side model includes the modeling of the impeller, permanent magnet synchronous generator, machine-side converter and grid-side converter of the direct-drive wind turbine. The impeller is used to convert wind energy into mechanical energy, and the mechanical energy is converted into electromagnetic power through the permanent magnet synchronous generator. The electromagnetic power is transmitted to the power grid by the machine-side converter and the grid-side converter.

[0075] The wind power is:

[0076]

[0077] Where ρ is the air density, S wind is the swept area, and v is the wind speed.

[0078] The mechanical power converted from wind power by the impeller is:

[0079]

[0080] Among them, C p is the wind energy utilization coefficient, and its size depends on the efficiency of the interaction between wind and wind wheel during the energy conversion process. Figure 3 As shown in the figure, the stator voltage expression can be obtained from the equivalent circuit of the main circuit on the machine side:

[0081] U s =E+R s I s +jω s L s I s =jω r ψ f +R s I s +jω s L s I s ;

[0082] Where U s is the stator voltage, I s is the stator current, L s is the stator inductance, R s is the stator resistance, ω s is the stator angular velocity, ω r is the rotor angular velocity, ψ f is the stator flux.

[0083] Since the control of the converter is based on a two-term rotating coordinate system, each variable is decomposed into dq, and the d-axis of the dq rotating coordinate system is set to the direction of the permanent magnet flux of the direct-drive generator, and the voltage equation of the main circuit on the machine side in the synchronous rotating coordinate system is obtained:

[0084]

[0085] At this time, the expressions of active power and reactive power on the generator side are:

[0086]

[0087] The torque expression is:

[0088]

[0089] The machine side adopts rotor magnetic field oriented vector control, and the d axis is located in the magnetic flux direction of the rotor permanent magnet. sd = 0, so that the motor has no d-axis armature reaction, that is, the direct axis does not contribute torque, and all the current of the motor is used to generate electromagnetic torque, which can simplify the control, and then:

[0090]

[0091]

[0092]

[0093] From the direct-drive wind turbine control block diagram, the power outer loop control model of the machine-side converter is:

[0094]

[0095] The current inner loop control model of the machine-side converter is:

[0096]

[0097] In this embodiment, the electromagnetic power model of the machine-side converter includes:

[0098]

[0099] Where P dc is the electromagnetic power, ω r is the rotor angular velocity, T e is the electromagnetic torque, P n is the pole pair number, ψ f is the stator flux, i sq is the stator current.

[0100] In the stability analysis of direct-drive wind turbines connected to the grid, the large capacitor in the DC link isolates the machine side from the grid side, so that the machine side dynamics have little effect on the small disturbance dynamic model of the grid-connected system. Therefore, the wind turbine and the machine-side converter are equivalent to a constant power source, and it is assumed that the output power of the machine-side converter remains unchanged under the time scale studied, and its dynamic influence is ignored.

[0101] like Figure 4 As shown, based on the grid-side topology and control link of the direct-drive wind turbine, a small disturbance dynamic model of the direct-drive wind power system grid-connected system is established;

[0102] The machine side and grid side of the direct-drive wind turbine are connected by a back-to-back structure, such as Figure 5 As shown in the figure, the schematic diagram of power transmission between the machine side and the grid side is shown. From the topology diagram, the power on the capacitor in the back-to-back DC link is:

[0103]

[0104] Where P s is the active power output by the machine-side converter, P dc is the active power of the input grid-side converter, C1 is the capacitor on the back-to-back link, U dc is the capacitor voltage on the back-to-back DC link.

[0105] In order to make the DC link have no power loss, that is, P s =P dc According to the above formula, it can be deduced that U dc This goal is achieved by the voltage outer loop of the grid-side converter.

[0106] Due to the presence of large capacitors in the DC link, the impact of the generator-side dynamics on the grid side is minimal. Therefore, the generator side is equivalent to a constant power source, which is connected to the grid side through a large capacitor. Its output power is:

[0107] P dc =U dc I dc ;

[0108] Where P dc is the equivalent output power on the machine side, U dc is the voltage of capacitor C1 on the DC link, I dc This is the back-to-back DC link output current.

[0109] For the grid-side converter, the power transmitted from the DC link is:

[0110]

[0111] Where U cd , U cqare the d-axis and q-axis components of the grid-side converter output voltage, I cd ,I cq They are the d-axis and q-axis components of the grid-side converter output current respectively;

[0112] refer to Figure 4 , the terminal voltage equation of the grid-side converter in the dq coordinate system:

[0113]

[0114] In the formula, u d 、u q are the voltages of the grid side through the filter inductor, s is the differential symbol d / dt, L g is the grid-side filter inductor, ω1 is the fundamental angular frequency.

[0115] refer to Figure 5 , the current in the DC link has the following relationship:

[0116] I dc +I1=I2→I dc +sC1U dc =I2;

[0117] In this embodiment, in step S20, the current inner loop control model of the grid-side converter includes:

[0118]

[0119] Where U cd , U cq are the d-axis and q-axis components of the grid-side converter output voltage, respectively. c (s) is the current inner loop transfer function, I cdref ,I cqref are the d-axis and q-axis components of the grid-side converter output current reference value, I cd ,I cq are the d-axis and q-axis components of the grid-side converter output current, ω1 is the fundamental angular frequency, L g It is the grid-side filter inductor.

[0120] By establishing a current inner loop control model in the dq axis coordinate system, the grid-side converter can quickly respond to changes in the system current, achieve more accurate current control, reduce the dynamic response time of the system, and improve the overall control performance; the current inner loop control model is based on the filter inductor L g The dynamic adjustment of the fundamental angular frequency ω1 can effectively suppress the current fluctuation in the system under different working conditions, ensure the voltage and current stability of the grid-side converter, and reduce the impact of small signal disturbances on system stability.

[0121] As a preference of the above embodiment, in step S20, the voltage outer loop control model includes:

[0122]

[0123] In the formula, I cdref ,I cqref are the d-axis and q-axis components of the grid-side converter output current reference value, U dc is the DC side voltage, U dcref is the DC side voltage reference value, H u (s) is the transfer function of the voltage outer loop.

[0124] make Used to characterize the voltage outer loop transfer function, after small signal conversion, we have:

[0125] Δi cdqref =G uw ΔU dc ;

[0126] In the formula, Δi cdqref is the small signal component of the dq axis of the grid-side converter output current reference value, G uw is the transfer function of the voltage outer loop, ΔU dc is the small signal value of the DC side voltage;

[0127] Through the voltage outer loop transfer function G uw With the introduction of , the system can quickly respond to changes in DC voltage and quickly adjust the reference value of the grid-side converter output current, thereby improving the dynamic response speed and control accuracy of the system; the small signal model ensures that the DC side voltage can accurately follow the reference value Δi under different load conditions through real-time feedback control of the voltage. cdqref , effectively reducing the impact of voltage fluctuations on system stability and improving the voltage stability of the grid-connected system.

[0128] The control link of the grid-connected system is established in the dq coordinate system, while the grid voltage is based on the abc three-phase coordinate system. The wind power grid-connected system uses a phase-locked loop to track the system link to maintain synchronization. In this process, small disturbances in the phase-locked loop will also affect the output of the converter. In this paper, the dq coordinate system established by the actual phase angle in the system is called the main circuit coordinate system, and each component is represented by the superscript "g". Variables without a superscript in the following text are assumed to be in the main circuit coordinate system; the coordinate system established based on the phase angle of the phase-locked loop output is called the control coordinate system, and each component is represented by the superscript "c".

[0129] Among them, in step S20, if Figure 6 As shown in the figure, the principle diagram of the phase-locked loop is shown, and the control model considering the influence of small disturbances of the phase-locked loop (PLL) on the grid-connected point voltage includes:

[0130]

[0131] In the formula, ω pll is the phase-locked loop output angular frequency, H pll (s) is the phase-locked loop transfer function, u q is the q-axis component of the grid-side converter output voltage after the filter, θ pll is the phase-locked loop output phase angle, s is the differential symbol d / dt, k p , k i They are the proportional and integral control parameters of the phase-locked loop PI controller respectively.

[0132] By introducing the small signal transfer function H of the phase-locked loop pll (s), can accurately track the phase angle change of the grid-connected point voltage, ensure the real-time synchronization of the system voltage, and reduce the voltage phase deviation caused by small disturbances; the phase-locked loop can accurately adjust the output angular frequency ω pll And update the phase angle θ in real time pll , which can quickly respond to changes in grid frequency and ensure the synchronization of grid-connected voltage and grid frequency.

[0133] The phase-locked loop output disturbance angle can be obtained from the above formula:

[0134]

[0135] In order to express the influence of small disturbance of the phase-locked loop on the grid voltage, the following transfer function is used:

[0136]

[0137] In the formula, K pll To characterize the transfer function of the phase-locked loop disturbance, They are the d-axis and q-axis small signal components of the grid-side converter output voltage after filtering in the main circuit coordinate system, They are respectively the d-axis and q-axis small signal components of the grid-side converter output voltage after filtering in the control coordinate system.

[0138] Adding a small voltage signal disturbance at the grid connection point, the system dq system has:

[0139]

[0140] In the formula, u pcc is the actual voltage at the grid connection point, U pcc is the steady-state voltage at the grid connection point, Δu pcc is the small disturbance signal of the grid-connected point voltage, The d-axis and q-axis steady-state components of the grid-side converter output voltage in the main circuit coordinate system after filtering are: They are respectively the d-axis and q-axis steady-state components of the grid-side converter output voltage after filtering in the control coordinate system.

[0141] Substituting the above formula into the small disturbance transformation relationship expression of the variables of the system dq system and the control dq system, the small disturbance transformation relationship expression of the variables of the grid-side terminal voltage and current in the system dq system and the control dq system can be obtained:

[0142]

[0143]

[0144]

[0145] Then we can get:

[0146]

[0147] As a preferred embodiment of the above, in step S20, the grid-side small disturbance dynamic model, considering the small disturbance, describes the small signal relationship model between the voltage and current of the grid-side converter in the dq rotating coordinate system, including:

[0148]

[0149] Among them, Δu dq is the voltage dq axis small signal component of the grid-side converter after filtering, Δu cdq is the dq-axis small signal component of the grid-side converter output voltage, Δi cdqref is the dq-axis small signal component of the grid-side converter output current reference value, Δi cdq is the small signal component of the dq axis output current of the grid-side converter, G c is the current inner loop transfer function, G l is the transfer function of the filter link, G o is the coupling impedance transfer function.

[0150] By describing the small signal model of voltage and current in the dq rotating coordinate system, this technical solution can quickly identify the impact of small disturbances on the voltage and current of the system, thereby improving the dynamic response performance of the system, ensuring that the converter can quickly adjust the output when facing external disturbances and reducing the response time; the coupling impedance transfer function G o It helps to reduce the coupling effect between different components in the system, so that the system can better maintain the stability of voltage and current when facing small disturbances, improve anti-disturbance performance, and reduce the impact of the external environment on system operation; through the filtering link transfer function G l The output signal is filtered. The model can effectively suppress harmonics and other high-frequency components, improve the system power quality, and ensure the stable operation of the system under different wind turbine active output conditions.

[0151] In this embodiment, in step S20, the grid-side small disturbance dynamic model, considering the small disturbance impact model of the phase-locked loop (PLL) on the grid-connected point voltage, includes:

[0152]

[0153] In the formula, are the transfer functions that characterize the influence of small disturbance of the phase-locked loop on the voltage and current of the grid-side generator, G c is the current inner loop transfer function, G o is the coupling impedance transfer function, Respectively represent the dq-axis small signal components of the grid-side converter output voltage and current in the system coordinate system.

[0154] The small perturbation transfer function of voltage and current is introduced through the phase-locked loop (PLL) model and It can accurately track the phase change of the grid-connected point voltage, ensure the voltage phase is synchronized with the grid, help reduce the synchronization deviation caused by voltage fluctuations, and improve the stability of the system; the current inner loop transfer function G c The introduction of the coupling impedance transfer function G improves the dynamic response capability of the system when small disturbances occur. The system can quickly adjust the current and compensate for the voltage disturbance at the grid connection point in time, ensuring the smooth operation of the system when the wind power output changes. o The introduction of effectively reduces the mutual coupling interference between different modules within the system, improves the system's anti-interference ability under external disturbance conditions, and thus improves the system's operating stability; through small signal analysis in the dq-axis rotating coordinate system, the system can accurately describe the changing trends of voltage and current, ensure high-precision control of the grid-side converter under dynamic operating conditions, and help improve the overall efficiency and stability of the wind power grid-connected system; considering the impact of the phase-locked loop on the grid-connected point voltage, the system can reduce the impact of external grid fluctuations on the operation of the wind power grid-connected system, and ensure the system's stable grid connection when the wind turbine output fluctuates.

[0155] Among them, in step S30, the small signal model of the DC link voltage is obtained by connecting the machine side and the grid side through a back-to-back DC link based on the topological structure and active power transmission relationship of the DC link, including:

[0156]

[0157] Where U cd , U cq are the d-axis and q-axis components of the grid-side converter output voltage, I cd ,I cq are the d-axis and q-axis components of the grid-side converter output current, I dcis the back-to-back DC link output current, U dc is the voltage of capacitor C1 in the DC link.

[0158] Through the small signal model of the DC link, the system can accurately analyze and predict the dynamic changes of voltage and current, enhancing the system's response speed and control accuracy to input disturbances; through the dq axis small signal analysis of voltage and current, the system can effectively monitor the DC capacitor U dc and output current I dc changes, ensuring voltage stability at different wind turbine output levels and reducing the impact of fluctuations on system operation; by accurately describing the relationship between DC link voltage and current, the model can improve the system's anti-interference ability when facing grid voltage fluctuations and wind turbine output changes, ensuring stable system operation.

[0159] Get the small signal model of the current loop reference value:

[0160]

[0161] make

[0162] Wherein, in step S30, the machine side and the grid side are connected through a back-to-back DC link to obtain a small signal model of the current loop reference value, including:

[0163] Δi cdqref =G uw G w (G vi Δi cdq +G vu Δu cdq );

[0164] In the formula, G w To characterize the influence factor of output level on wind turbine impedance, G vi is the DC link current small signal transfer function, G vu is the DC link voltage small signal transfer function, Δu cdq is the dq-axis small signal component of the grid-side converter output voltage, Δi cdq It is the small signal component of the dq axis output current of the grid-side converter.

[0165] Through the current reference value provided by the small signal model, the system can accurately adjust the output of the current loop and improve the current control accuracy, which is crucial to maintain a stable current output, especially when the fan output fluctuates; the small signal transfer function G vi and G vu The introduction of can help the system quickly respond to changes in DC current and voltage, optimize the dynamic response capability of current loop control, and reduce current fluctuations caused by power changes; by analyzing the fan output level Gw The impact on impedance allows the system to better adapt to different load conditions, maintain system stability, and avoid system instability caused by output fluctuations; the small signal model can better handle grid voltage fluctuations and external disturbances, and ensure stable operation of the system under disturbance conditions by adjusting the reference value of the current loop in real time.

[0166] The electric power expression of the DC link can be used to establish I dc With P dc Therefore, G w It can be used to characterize the factors affecting the output level on the wind turbine impedance:

[0167] In this embodiment, in step S40, a wind power grid-connected system impedance model including wind turbine output level influencing factors is established. The model of wind turbine output level influencing factors includes:

[0168]

[0169] In the formula, G w To characterize the influence factor of output level on wind turbine impedance, P dc is the equivalent output power on the machine side, U dc is the voltage of capacitor C1 in the DC link, C1 is the capacitance in the back-to-back link, and s is the differential symbol d / dt.

[0170] By establishing the fan output level influencing factor model G w , can be based on the actual output power P of the fan dc and DC voltage U dc Dynamically adjust the system impedance to ensure that the system maintains high-precision impedance matching under different loads and wind turbine output levels; by considering the relationship between the machine-side output power and the DC voltage, the system can reflect the impact of wind turbine output changes on impedance in real time, thereby quickly adjusting the impedance of the grid-connected system, improving the dynamic response speed, and ensuring that the system can quickly adapt to fluctuations in wind turbine output; through the capacitor C1 and differential operator s in the model, the system can accurately analyze the impact of changes in the DC link capacitor voltage on impedance, thereby improving the system's voltage stability, especially when large-scale wind turbine output fluctuates, and can effectively suppress voltage fluctuations; by accurately controlling the impact of wind turbine output levels on impedance, the system can reduce voltage and current fluctuations caused by power fluctuations, thereby improving the power quality of the grid-connected system and reducing harmonic generation.

[0171] Substituting it into the grid-side current loop small signal model considering the influence of the phase-locked loop, we get:

[0172]

[0173] As a preferred embodiment of the above, in step S40, based on the initial impedance model of the grid side, the active output of the wind turbine is used as an independent variable to establish a wind power grid-connected system impedance model including factors affecting the wind turbine output level. The equivalent impedance of the direct-drive wind turbine itself is defined as the ratio of voltage to current. The wind power grid-connected system impedance model includes:

[0174]

[0175] In the formula, Z pmsg is the impedance model of wind power grid-connected system, Δu cdq is the dq-axis small signal component of the grid-side converter output voltage, Δi cdq is the small signal component of the dq axis output current of the grid-side converter, G c is the current inner loop transfer function, G uw is the voltage outer loop transfer function, G o is the coupling impedance transfer function, are the transfer functions that characterize the influence of small disturbance of the phase-locked loop on the voltage and current of the grid-side generator, G w To characterize the influence factor of output level on wind turbine impedance, G vi is the DC link current small signal transfer function, G vu is the small signal transfer function of the DC link voltage.

[0176] Based on the initial impedance model on the grid side, the wind turbine active output is taken as the independent variable and the output level influencing factor G is introduced. w , it can accurately analyze the dynamic impact of different wind turbine output levels on system impedance. This enables the wind power grid-connected system to maintain accurate impedance matching under different working conditions and improve the stability of system operation.

[0177] Coupling impedance transfer function G o It helps to reduce the coupling interference between different components and improve the system's ability to resist external disturbances. Whether it is wind turbine output fluctuations or grid-side disturbances, the system can remain stable and reduce voltage or current fluctuations caused by coupling effects.

[0178] Small perturbation transfer function through a phase-locked loop (PLL) and The system can better adjust the phase and amplitude of the grid-side voltage. This adjustment ensures that the system can maintain precise voltage control under conditions of voltage disturbance or output fluctuation, thereby improving the power quality of the grid-connected system.

[0179] DC link current and voltage small signal transfer function G c and G uwThe introduction of , can monitor and adjust the current and voltage of the DC link in real time, ensuring that the system can achieve accurate current control under different output conditions. This helps to reduce the impact of power fluctuations on system stability and improve the efficiency and reliability of the grid-connected system.

[0180] The introduction of wind turbine active output as an independent variable enables the system to dynamically adjust the impedance model according to the output level of the wind turbine, ensuring that the system can maintain stable operation under various load conditions, reducing the interference of current and voltage fluctuations on system operation, and improving the overall stability of the wind power grid-connected system.

[0181] The present invention also includes a wind power grid-connected system impedance modeling device considering the active output of wind power, using the above method, such as Figure 7 As shown, including:

[0182] The machine side model building unit is used to build the machine side model of the direct-drive wind turbine. The machine side model is based on the machine side topology and control link of the direct-drive wind turbine, adopts the dq rotating coordinate system, and places the d axis along the magnetic flux direction of the permanent magnet of the direct-drive generator;

[0183] A grid-side small disturbance dynamic model building unit is used to build a grid-side small disturbance dynamic model of a direct-drive wind turbine based on a machine-side model. The grid-side small disturbance dynamic model is based on a grid-side topology and control links. The control links include a voltage outer loop control model and a current inner loop control model, and consider the small disturbance effect of a phase-locked loop (PLL) on the grid-connected point voltage.

[0184] A grid-side initial impedance model building unit is used to connect the generator side and the grid side through a back-to-back DC link, to treat the generator-side converter output power as a constant power source, to ignore the influence of the generator-side dynamics on the grid-side small disturbance dynamic model, and to build an initial impedance model of the grid side;

[0185] The wind turbine output level impedance model improvement unit is used to improve the impedance model based on the initial impedance model on the grid side, taking the wind turbine active output as the independent variable, and establish a wind power grid-connected system impedance model that includes the wind turbine output level influencing factors;

[0186] The system stability evaluation unit is used to calculate the equivalent impedance of the wind power grid-connected system under different active output conditions based on the wind power grid-connected system impedance model, and to evaluate the stability of the system under different active output conditions.

[0187] See also Figure 8 A computer device 400 provided in an embodiment of the present application includes: a processor 410 and a memory 420, wherein the memory 420 stores a computer program executable by the processor 410, and when the computer program is executed by the processor 410, the above method is executed.

[0188] The embodiment of the present application further provides a storage medium 430 on which a computer program is stored. When the computer program is run by the processor 410, the above method is executed.

[0189] Among them, the storage medium 430 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable red-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, disk or optical disk.

[0190] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0191] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0192] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0193] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0194] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0195] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0196] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0197] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A wind power grid-connected system impedance modeling method considering wind power active output, characterized in that: The steps include: S10: establishing a machine-side model of the direct-drive wind turbine, wherein the machine-side model is based on the machine-side topological structure and control link of the direct-drive wind turbine, adopts a dq rotating coordinate system, and sets the d-axis along the magnetic flux direction of the permanent magnet of the direct-drive generator; S20: Based on the machine-side model, a small disturbance dynamic model of the direct-drive wind turbine is established. The small disturbance dynamic model of the direct-drive wind turbine is based on the grid-side topology and control link. The control link includes a voltage outer loop control model and a current inner loop control model, and considers the small disturbance effect of the phase-locked loop on the grid connection point voltage. S30: connecting the machine side and the grid side through a back-to-back DC link, treating the output power of the machine side converter as equivalent to a constant power source, ignoring the influence of the machine side dynamics on the small disturbance dynamic model of the grid side, and constructing an initial impedance model of the grid side; S40: Based on the initial impedance model of the grid side, taking the active output of the wind turbine as an independent variable, an impedance model of the wind power grid-connected system including factors affecting the output level of the wind turbine is established; S50: Based on the wind power grid-connected system impedance model, the equivalent impedance of the wind power grid-connected system under different active output conditions is calculated, and the stability of the system under different active output conditions is evaluated.

2. The wind power grid-connected system impedance modeling method considering wind power active output according to claim 1 is characterized in that: In step S20, the current inner loop control model of the grid-side converter includes: Where U cd , U cq are the d-axis and q-axis components of the grid-side converter output voltage, respectively. c (s) is the current inner loop transfer function, I cdref ,I cqref are the d-axis and q-axis components of the grid-side converter output current reference value, I cd ,I cq are the d-axis and q-axis components of the grid-side converter output current, ω1 is the fundamental angular frequency, L g It is the grid-side filter inductor.

3. The wind power grid-connected system impedance modeling method considering wind power active output according to claim 1 is characterized in that: In step S20, the voltage outer loop control model includes: In the formula, I cdref ,I cqref are the d-axis and q-axis components of the grid-side converter output current reference value, U dc is the DC side voltage, U dcref is the DC side voltage reference value, H u (s) is the transfer function of the voltage outer loop.

4. The wind power grid-connected system impedance modeling method considering wind power active output according to claim 1 is characterized in that: In step S20, the control model considering the influence of small disturbance of the phase-locked loop on the grid-connected point voltage includes: In the formula, ω pll is the phase-locked loop output angular frequency, H pll (s) is the phase-locked loop transfer function, u q is the q-axis component of the grid-side converter output voltage after the filter, θ pll is the phase-locked loop output phase angle, s is the differential symbol d / dt, k p , k i They are the proportional and integral control parameters of the phase-locked loop PI controller respectively.

5. The wind power grid-connected system impedance modeling method considering wind power active output according to claim 1 is characterized in that: In step S20, the grid-side small disturbance dynamic model, under consideration of small disturbances, describes the small signal relationship model between the voltage and current of the grid-side converter in the dq rotating coordinate system, including: Among them, Δu dq is the voltage dq axis small signal component of the grid-side converter after filtering, Δu cdq is the dq-axis small signal component of the grid-side converter output voltage, Δi cdqref is the dq-axis small signal component of the grid-side converter output current reference value, Δi cdq is the small signal component of the dq axis output current of the grid-side converter, G c is the current inner loop transfer function, G l is the transfer function of the filter link, G o is the coupling impedance transfer function.

6. The wind power grid-connected system impedance modeling method considering wind power active output according to claim 1 is characterized in that: In step S20, the grid-side small disturbance dynamic model, considering the small disturbance impact of the phase-locked loop on the grid-connected point voltage, includes: In the formula, are the transfer functions that characterize the influence of small disturbance of the phase-locked loop on the voltage and current of the grid-side generator, G c is the current inner loop transfer function, G o is the coupling impedance transfer function, Respectively represent the dq-axis small signal components of the grid-side converter output voltage and current in the system coordinate system.

7. The wind power grid-connected system impedance modeling method considering wind power active output according to claim 1 is characterized in that: In step S30, the small signal model of the DC link voltage obtained by connecting the machine side and the grid side through the back-to-back DC link and the topological structure of the DC link and the active power transmission relationship includes: Where U cd , U cq are the d-axis and q-axis components of the grid-side converter output voltage, I cd ,I cq are the d-axis and q-axis components of the grid-side converter output current, I dc is the back-to-back DC link output current, U dc is the voltage of capacitor C1 in the DC link.

8. The wind power grid-connected system impedance modeling method considering wind power active output according to claim 1 is characterized in that: In step S30, the small signal model of the current loop reference value is obtained by connecting the machine side and the grid side through the back-to-back DC link, including: Δi cdqref =G uw G w (G vi Δi cdq +G vu Δu cdq ); In the formula, G w To characterize the influence factor of output level on wind turbine impedance, G vi is the DC link current small signal transfer function, G vu is the DC link voltage small signal transfer function, Δu cdq is the dq-axis small signal component of the grid-side converter output voltage, Δi cdq It is the small signal component of the dq axis output current of the grid-side converter.

9. The wind power grid-connected system impedance modeling method considering wind power active output according to claim 1 is characterized in that: In step S40, the wind power grid-connected system impedance model including the wind turbine output level influencing factors is established, and the model of the wind turbine output level influencing factors includes: In the formula, G w To characterize the influence factor of output level on wind turbine impedance, P dc is the equivalent output power on the generator side, U dc is the voltage of capacitor C1 in the DC link, C1 is the capacitance in the back-to-back link, and s is the differential symbol d / dt.

10. The wind power grid-connected system impedance modeling method considering wind power active output according to claim 1, characterized in that: In step S40, based on the initial impedance model of the grid side, the wind turbine active output is used as an independent variable to establish a wind power grid-connected system impedance model including factors affecting the wind turbine output level. The direct-drive wind turbine's own equivalent impedance is defined as the ratio of voltage to current. The wind power grid-connected system impedance model includes: In the formula, Z pmsg is the impedance model of wind power grid-connected system, Δu cdq is the dq-axis small signal component of the grid-side converter output voltage, Δi cdq is the small signal component of the dq axis output current of the grid-side converter, G c is the current inner loop transfer function, G uw is the voltage outer loop transfer function, G o is the coupling impedance transfer function, are the transfer functions that characterize the influence of small disturbance of the phase-locked loop on the voltage and current of the grid-side generator, G w To characterize the influence factor of output level on wind turbine impedance, G vi is the DC link current small signal transfer function, G vu is the small signal transfer function of the DC link voltage.

11. A wind power grid-connected system impedance modeling device considering wind power active output, characterized in that: Use of the method according to any one of claims 1 to 10, comprising: A machine-side model building unit is used to build a machine-side model of the direct-drive wind turbine, wherein the machine-side model is based on the machine-side topological structure and control link of the direct-drive wind turbine, adopts a dq rotating coordinate system, and sets the d-axis along the magnetic flux direction of the permanent magnet of the direct-drive generator; A grid-side small disturbance dynamic model establishment unit is used to establish a grid-side small disturbance dynamic model of the direct-drive wind turbine based on the machine-side model, wherein the grid-side small disturbance dynamic model is based on the grid-side topology and control links, wherein the control links include a voltage outer loop control model and a current inner loop control model, and consider the small disturbance effect of the phase-locked loop on the grid connection point voltage; A grid-side initial impedance model building unit is used to connect the machine side and the grid side through a back-to-back DC link, to treat the output power of the machine-side converter as a constant power source, to ignore the influence of the machine-side dynamics on the small disturbance dynamic model of the grid side, and to build an initial impedance model of the grid side; A wind turbine output level impedance model improvement unit is used to establish a wind power grid-connected system impedance model including wind turbine output level influencing factors based on the initial impedance model of the grid side and taking the wind turbine active output as an independent variable; The system stability evaluation unit is used to calculate the equivalent impedance of the wind power grid-connected system under different active output conditions based on the wind power grid-connected system impedance model, and evaluate the stability of the system under different active output conditions.

12. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 10 is implemented.

13. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 10 is implemented.

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