General impedance acquisition method and system under multiple control structure of double-fed wind turbine generator set

Abstract

The application discloses a kind of universal impedance acquisition method and system under the multiple control structure of doubly-fed wind turbine, belong to new energy power generation grid-connected modeling and stability analysis field.Method includes: determine the additional control type distinguished with input signal source and output signal action position;The small signal transfer relationship of stator and rotor voltage and current of doubly-fed asynchronous generator, the small signal transfer relationship of direct current voltage, the end voltage-phase transfer relationship caused by phase-locked loop is respectively established, based on additional control type, the small signal transfer relationship of modulation signal and its port voltage small signal transfer relationship of grid-side converter and machine-side converter under the multiple control structure are respectively deduced;All small signal relationships are solved simultaneously, and frequency domain admittance model is obtained, and general impedance model is obtained by inversion.The application realizes the generalization construction of impedance model by modular modeling and matrix operation, solves the problem that impedance modeling process is complex, dependent on specific control structure and poor flexibility in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of grid-connected modeling and stability analysis of new energy power generation, and in particular relates to a general impedance acquisition method and system under multiple control structures of doubly fed wind turbine units. Background Technology

[0002] With the continuous expansion of the grid-connected scale of new energy power generation, electromagnetic transient simulation has become an important means of analyzing system stability. Currently, the electromagnetic transient models of doubly-fed induction generator (DFIG) wind turbines are typically encapsulated in code, presenting their control structure and parameters as a black box to external users. This results in the model being unobservable, unmeasurable, and unmodifiable, severely limiting the accuracy and flexibility of system simulation and stability analysis. To address these issues, existing technologies have proposed control structure and parameter identification methods based on impedance fitting. This method identifies the control structure and parameters of DFIG wind turbines by fitting theoretical analytical impedance with measured impedance. However, problems still exist in the process of obtaining the theoretical analytical impedance: First, existing methods for obtaining theoretical analytical impedance heavily rely on a deep understanding of linearization analysis methods and complex mathematical calculations. This process is cumbersome, has high technical barriers, and poor operability, making it difficult to widely apply in practical engineering. Second, existing impedance modeling methods for doubly-fed induction generator (DFIG) wind turbines are typically based on specific main circuit topologies and control structures, lacking versatility and flexibility. When the control structure changes, the entire impedance model must be re-derived, resulting in low modeling efficiency and failing to meet the needs of rapid simulation and stability analysis of grid-connected systems with multiple control structures. Summary of the Invention

[0003] To address or improve the problems existing in the prior art, this invention provides a universal impedance acquisition method and system for doubly-fed wind turbines under multiple control structures. This universal impedance acquisition method for doubly-fed wind turbines is adaptable to various control structures, has a simple derivation process, and is easy to implement in a program, thereby improving the efficiency and practicality of structured modeling.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a universal impedance acquisition method for multi-control structures of doubly-fed wind turbine generators, comprising: The additional control types for the doubly-fed induction generator (DFIG) wind turbine are determined. Each additional control is differentiated based on the source of the input signal and the position of the output signal. A first small-signal transmission relationship is established between the stator and rotor voltages and currents of the DFIG asynchronous generator. A second small-signal transmission relationship in the DC voltage frequency domain is established based on the instantaneous power balance relationship at the AC and DC ports. A third small-signal transmission relationship in the terminal voltage-phase frequency domain is established based on the phase-locked loop (PLL) control structure. The grid-side converter current in the three-phase stationary coordinate system is transformed to the dq synchronous rotating coordinate system to obtain the Park transformation transmission relationship of the grid-side converter current. Based on the additional control types, the third small-signal transmission relationship, and the Park transformation transmission relationship of the grid-side converter current, a fourth small-signal transmission relationship in the d and q axis modulation signal frequency domains under the multi-control structure of the grid-side converter is established. The fourth small-signal transmission relationship is transformed to the three-phase stationary coordinate system to obtain the first modulation signal transmission relationship. Based on the first modulation signal transmission relationship and the power circuit relationship of the DFIG wind turbine, a... The fifth small-signal transfer relationship of the grid-side converter port voltage in the frequency domain is obtained; the generator-side converter current in the three-phase stationary coordinate system is transformed to the dq synchronous rotating coordinate system to obtain the generator-side converter current Park transformation transfer relationship; based on the generator-side converter control structure, additional control type, and generator-side converter current Park transformation transfer relationship, the sixth small-signal transfer relationship of the d and q axis modulation signals in the frequency domain under the multi-control structure of the generator-side converter is established; the sixth small-signal transfer relationship is transformed to the three-phase stationary coordinate system to obtain the second modulation signal transfer relationship in the three-phase stationary coordinate system under the multi-control structure of the generator-side converter; based on the second modulation signal transfer relationship and the power circuit relationship of the doubly-fed induction generator (DFIG) wind turbine, the seventh small-signal transfer relationship of the generator-side converter port voltage in the frequency domain is established; based on the first, second, fifth, and seventh small-signal transfer relationships, the frequency domain admittance model of the DFIG wind turbine is obtained by solving the system of equations simultaneously; the frequency domain impedance model of the DFIG wind turbine is obtained by inverting the frequency domain admittance model of the DFIG wind turbine.

[0005] Furthermore, the additional control types include a first additional control, a second additional control, a third additional control, and a fourth additional control; wherein, the first additional control input signal is the d-axis and q-axis capacitor current of the doubly-fed induction generator (DFIG) wind turbine, and the output signal is added to the d-axis and q-axis modulation signal of the grid-side converter; the second additional control input signal is the d-axis and q-axis grid connection point voltage of the DFIG wind turbine, and the output signal is added to the d-axis and q-axis modulation signal of the grid-side converter; the third additional control input signal is the three-phase AC current of the DFIG wind turbine on the generator side, and the output signal is added to the a-axis, b-axis, and c-axis modulation signal of the generator side converter; the fourth additional control input signal is the sampled value of the three-phase AC current of the DFIG wind turbine on the generator side, and the output signal is the feedback value of the three-phase AC current on the generator side.

[0006] Furthermore, based on the additional control type, the third small-signal transmission relationship, and the Park transform transmission relationship of the grid-side converter current, a fourth small-signal transmission relationship in the frequency domain of the d-axis and q-axis modulation signals under the multi-control structure of the grid-side converter is established, including:

[0007]

[0008]

[0009] in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulated signals of the d-axis and q-axis modulated signals of the network-side converter, respectively. It is a small signal in the frequency domain of DC voltage; For small AC terminal voltage signals; This is the small signal of AC current from the grid-side converter; , These are fifth-order matrices for the grid-side current controller and the DC voltage controller, respectively. , These are the fifth-order diagonal matrices representing the first and second additional controls, respectively. When neither the first nor the second additional control is present, [the matrix will be...]. or =0; For the decoupling coefficients of the grid-side converter current controller; , , , These are the fifth-order coefficient matrices representing the frequency domain small-signal propagation relationship of AC current in the grid-side converter; The impedance of the filter capacitor is given under small signal frequency sequences.

[0010] Furthermore, based on the machine-side converter control structure, additional control types, and the Park transform transfer relationship of the machine-side converter current, a sixth small-signal transfer relationship in the frequency domain of the d-axis and q-axis modulation signals under the multi-control structure of the machine-side converter is established, including:

[0011]

[0012]

[0013] in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulation signals of the d-axis and q-axis modulated signals of the machine-side converter, respectively. This is the small signal of the stator winding current; This is the small signal of AC current from the grid-side converter; For small AC terminal voltage signals; For worsening; For machine-side current controller, , These are fifth-order matrices for active and reactive power controllers, respectively. This represents the decoupling coefficient of the machine-side current loop. The stator-to-rotor turns ratio, , , These are the fifth-order coefficient matrices of the active power frequency domain small-signal signal, respectively. , , These are the fifth-order coefficient matrices of the small-signal reactive power in the frequency domain; For the third additional control, a fifth-order diagonal matrix is ​​used. When the third additional control is not present, [the matrix is...]. Take a fifth-order identity matrix.

[0014] In a second aspect, the present invention provides a universal impedance acquisition device for a doubly-fed wind turbine with multiple control structures, comprising: The identification module is used to determine the additional control type of the doubly fed wind turbine; each additional control is distinguished based on the source of the input signal and the location of the output signal. The first processing module is used to establish the first small signal transmission relationship between the stator and rotor voltages and currents based on the relationship between the stator and rotor voltages and currents of the doubly fed asynchronous generator. The second processing module is used to establish the second small-signal transmission relationship in the DC voltage frequency domain based on the instantaneous power balance relationship between the AC and DC ports. The third processing module is used to establish the third small-signal transmission relationship in the frequency domain of terminal voltage-phase based on the phase-locked loop control structure; to convert the grid-side converter current in the three-phase stationary coordinate system to the dq synchronous rotating coordinate system to obtain the grid-side converter current Park transformation transmission relationship; to establish the fourth small-signal transmission relationship in the frequency domain of d and q axis modulation signals under the multi-control structure of the grid-side converter based on the additional control type, the third small-signal transmission relationship, and the grid-side converter current Park transformation transmission relationship; to convert the fourth small-signal transmission relationship to the three-phase stationary coordinate system to obtain the first modulation signal transmission relationship; and to establish the fifth small-signal transmission relationship in the frequency domain of grid-side converter port voltage based on the first modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine. The fourth processing module is used to convert the machine-side converter current in the three-phase stationary coordinate system to the dq synchronous rotating coordinate system to obtain the machine-side converter current Park transformation transmission relationship; based on the machine-side converter control structure, additional control type, and machine-side converter current Park transformation transmission relationship, it establishes the sixth small-signal transmission relationship in the frequency domain of the d and q axis modulation signals under the multi-control structure of the machine-side converter; it converts the sixth small-signal transmission relationship to the three-phase stationary coordinate system to obtain the second modulation signal transmission relationship in the three-phase stationary coordinate system of the multi-control structure of the machine-side converter; according to the second modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine, it establishes the seventh small-signal transmission relationship in the frequency domain of the machine-side converter port voltage. The first solution module is used to solve the simultaneous solution based on the first small-signal transmission relationship, the second small-signal transmission relationship, the fifth small-signal transmission relationship and the seventh small-signal transmission relationship to obtain the frequency domain admittance model of the doubly fed wind turbine. The second solution module is used to invert the frequency domain admittance model of the doubly fed wind turbine to obtain the frequency domain impedance model of the doubly fed wind turbine.

[0015] Furthermore, the additional control types include a first additional control, a second additional control, a third additional control, and a fourth additional control; wherein, the first additional control input signal is the d-axis and q-axis capacitor current of the doubly-fed induction generator (DFIG) wind turbine, and the output signal is added to the d-axis and q-axis modulation signal of the grid-side converter; the second additional control input signal is the d-axis and q-axis grid connection point voltage of the DFIG wind turbine, and the output signal is added to the d-axis and q-axis modulation signal of the grid-side converter; the third additional control input signal is the three-phase AC current of the DFIG wind turbine on the generator side, and the output signal is added to the a-axis, b-axis, and c-axis modulation signal of the generator side converter; the fourth additional control input signal is the sampled value of the three-phase AC current of the DFIG wind turbine on the generator side, and the output signal is the feedback value of the three-phase AC current on the generator side.

[0016] Furthermore, based on the additional control type, the third small-signal transmission relationship, and the Park transform transmission relationship of the grid-side converter current, a fourth small-signal transmission relationship in the frequency domain of the d-axis and q-axis modulation signals under the multi-control structure of the grid-side converter is established, including:

[0017]

[0018]

[0019] in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulated signals of the d-axis and q-axis modulated signals of the network-side converter, respectively. It is a small signal in the frequency domain of DC voltage; For small AC terminal voltage signals; This is the small signal of AC current from the grid-side converter; , These are fifth-order matrices for the grid-side current controller and the DC voltage controller, respectively. , These are the fifth-order diagonal matrices representing the first and second additional controls, respectively. When neither the first nor the second additional control is present, [the matrix will be...]. or =0; For the decoupling coefficients of the grid-side converter current controller; , , , These are the fifth-order coefficient matrices representing the frequency domain small-signal propagation relationship of AC current in the grid-side converter; for.

[0020] Furthermore, based on the machine-side converter control structure, additional control types, and the Park transform transfer relationship of the machine-side converter current, a sixth small-signal transfer relationship in the frequency domain of the d-axis and q-axis modulation signals under the multi-control structure of the machine-side converter is established, including:

[0021]

[0022]

[0023] in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulation signals of the d-axis and q-axis modulated signals of the machine-side converter, respectively. This is the small signal of the stator winding current; This is the small signal of AC current from the grid-side converter; For small AC terminal voltage signals; For worsening; For machine-side current controller, , These are fifth-order matrices for active and reactive power controllers, respectively. This represents the decoupling coefficient of the machine-side current loop. The stator-to-rotor turns ratio, , , These are the fifth-order coefficient matrices of the active power frequency domain small-signal signal, respectively. , , These are the fifth-order coefficient matrices of the small-signal reactive power in the frequency domain; For the third additional control, a fifth-order diagonal matrix is ​​used. When the third additional control is not present, [the matrix is...]. Take a fifth-order identity matrix.

[0024] In a third aspect, the present invention provides an electronic device including a processor and a memory, the processor being configured to execute a computer program stored in the memory to implement the method described above.

[0025] In a fourth aspect, the present invention provides a computer-readable storage medium storing at least one instruction which, when executed by a processor, implements the method described above.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: To address the problems of complex processes, poor versatility, and difficulty in adapting to changes in multiple control structures in existing impedance modeling methods for doubly-fed induction generator (DFIG) wind turbines, this invention first distinguishes the additional control types based on the source of the input signal and the location of the output signal. Second, it establishes the small-signal transmission relationships of stator and rotor voltage and current, the frequency domain small-signal transmission relationship of DC voltage, and the terminal voltage-phase transmission relationship of the phase-locked loop (PLL) control for the DFIG asynchronous generator. Then, combining the additional control types, through coordinate transformation and signal synthesis, it derives the frequency domain transmission relationships of the modulation signals and port voltages of the grid-side converter and the generator-side converter under multiple control structures. Finally, it solves all the small-signal transmission relationships simultaneously to obtain the frequency domain admittance model of the system, and obtains the universal impedance model through matrix inversion. This invention adopts a modular modeling method, transforming complex derivations into matrix operations, reducing modeling difficulty, improving computational efficiency, and flexibly adapting to different control structures, providing an effective technical means for the structured modeling and stability analysis of DFIG wind turbines. Attached Figure Description

[0027] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a topology diagram of a doubly fed wind turbine in an embodiment of the present invention; Figure 2 Here are the control block diagrams of the doubly fed wind turbine generator considering different additional controls in the embodiments of the present invention: (a) grid-side converter control block diagram; (b) turbine-side converter control block diagram. Figure 3 This is a flowchart of a general impedance acquisition method for a doubly fed wind turbine under a multi-control structure, according to an embodiment of the present invention. Figure 4 The following is a control block diagram of a doubly fed wind turbine implementation case in this invention: (a) grid-side converter control structure, (b) turbine-side converter control structure; Figure 5 This is a structural block diagram of a universal impedance acquisition device under a multi-control structure for a doubly fed wind turbine, according to an embodiment of the present invention. Figure 6 This is a structural block diagram of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0029] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0030] Example 1 This invention proposes a universal impedance acquisition method for doubly-fed induction generator (DFIG) wind turbines under multiple control structures. The topology of the DFIG wind turbine using this method is as follows: Figure 1 As shown, it includes: wind turbine 1, gearbox 2, asynchronous generator 3, machine-side converter 4, grid-side converter 5, and filter capacitor 6. , , This refers to the three-phase voltage at the grid connection point of the doubly-fed wind turbine. , , This represents the three-phase AC current of the grid-side converter, with the direction of outflow being positive. , , This is the three-phase alternating current on the stator side, with the direction of flow into the generator being positive. , , This is the three-phase alternating current on the generator side, with the direction of flow into the generator being positive. and For the filter resistors and inductors of the machine-side converter, and For the filter resistors and inductors of the grid-side converter, and These are the filter resistor 2 and the filter capacitor for the grid-side converter, respectively. For DC bus capacitors, This is the total voltage of the DC bus.

[0031] like Figure 3 As shown, a general impedance acquisition method under a multi-control structure for a doubly-fed wind turbine includes steps S1 to S7: S1. Determine the additional control type for the doubly fed wind turbine; whereby each additional control is distinguished based on the source of the input signal and the location of the output signal.

[0032] In one embodiment, the control block diagram of the doubly-fed wind turbine is as follows: Figure 2 As shown, its control structure includes machine-side converter control and grid-side converter control. The machine-side converter control includes active and reactive power control and machine-side AC current control; the grid-side converter control includes DC voltage control and grid-side AC current control.

[0033] Based on the common input and output signal types of additional controls, they are divided into four categories: first additional control, second additional control, third additional control, and fourth additional control; among them, the input signal for the first additional control is the d-axis and q-axis capacitor current of the doubly-fed wind turbine. , The output signal is added to the d-axis and q-axis modulation signals of the grid-side converter. Common controls include active damping control. The first additional control transfer function is used... This indicates that the second additional control input signal is the grid connection point voltage of the doubly-fed wind turbine's d and q axes. , The output signal is added to the d-axis and q-axis modulation signals of the grid-side converter. Common control methods include voltage feedforward control. The second additional control transfer function is used... The third additional control input signal is the three-phase AC current on the generator side of the doubly-fed wind turbine. , , The output signal is added to the modulation signals of the a, b, and c axes of the machine-side converter. Common control methods include proportional resonant control. The third additional control transfer function is used... The fourth additional control input signal is the sampled value of the three-phase AC current on the turbine side of the doubly-fed induction generator (DFIG), and the output signal is the feedback value of the three-phase AC current on the turbine side. Common controls include notch filters and low-pass filters. The transfer function of the fourth additional control is expressed using... express.

[0034] S2. Based on the relationship between the stator and rotor voltages and currents of the doubly fed asynchronous generator, establish the first small signal transmission relationship between the stator and rotor voltages and currents.

[0035] In one embodiment, based on the relationship between the stator and rotor voltages and currents of the doubly-fed asynchronous generator, the small-signal transmission relationship between the stator and rotor voltages and currents is established as shown in the following equation: (1) All quantities are transferred to a three-phase stationary coordinate system. and These are the small-signal values ​​for rotor winding voltage and current, respectively. and These are the small signals for stator winding voltage and current, respectively. , , , These are the fifth-order coefficient matrices of the DFIG frequency domain small-signal model, with all elements being 0 except for the elements listed below.

[0036] (2) (3) (4) (5) in, The rotor's angular velocity. For the perturbation frequency, , , For magnetizing inductance, , These are the stator winding resistance and inductance, respectively. , These represent the rotor winding resistance and inductance, respectively. j denotes an imaginary number.

[0037] (1,1) represents the element in the first row and first column of the fifth-order coefficient matrix.

[0038] (3,3) represents the element in the third row and third column of the fifth-order coefficient matrix.

[0039] S3. Based on the instantaneous power balance relationship between the AC and DC ports, establish the second small-signal transmission relationship in the DC voltage frequency domain.

[0040] In one embodiment, a DC voltage frequency domain small-signal is established based on the instantaneous power balance relationship between the AC and DC ports. The transitive relationship is shown in equation (6).

[0041] (6) in, This is the small signal of AC current for the grid-side converter. , , , These are the fifth-order coefficient matrices of the DC voltage frequency domain small-signal model, with all elements being 0 except for the elements listed below.

[0042] (7) (8) (9) (10) in, For the steady-state vector of the modulated voltage of the grid-side converter, This represents the steady-state vector of the AC current in the grid-side converter. For the steady-state vector of the modulated voltage of the machine-side converter, This is the steady-state vector of the AC current of the machine-side converter.

[0043] represents the conjugate of the steady-state vector of the modulated voltage of the grid-side converter; (2,1) and (2,3) represent the elements in the second row and first column of the fifth-order coefficient matrix and the elements in the second row and third column, respectively. Vdc This represents the steady-state value of the DC voltage. , Lf represents the AC filter inductor.

[0044] S4. Based on the phase-locked loop control structure, establish the third small-signal transmission relationship in the terminal voltage-phase frequency domain; convert the grid-side converter current in the three-phase stationary coordinate system to the dq synchronous rotating coordinate system to obtain the grid-side converter current Park transformation transmission relationship; based on the additional control type, the third small-signal transmission relationship, and the grid-side converter current Park transformation transmission relationship, establish the fourth small-signal transmission relationship in the d and q axis modulation signal frequency domain under the grid-side converter multi-control structure; convert the fourth small-signal transmission relationship to the three-phase stationary coordinate system to obtain the first modulation signal transmission relationship; based on the first modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine, establish the fifth small-signal transmission relationship in the grid-side converter port voltage frequency domain.

[0045] In one embodiment, step S4 includes steps S41 to S45: S41. Establish the small-signal transmission relationship between terminal voltage and phase in the frequency domain, including: Based on the phase-locked loop control structure, the small-signal transmission relationship between the terminal voltage and phase in the frequency domain is established as follows: (11) in, For small phase signals, For small AC terminal voltage signals, To pass the relation matrix, the expression is as follows: (12) in, The steady-state initial angle of the phase-locked loop (PLL) angle. The transfer function of the phase-locked loop. , For the perturbation frequency, This is the fundamental frequency. When using different phase-locked loop structures, only the fundamental frequency needs to be adjusted. In Make the necessary modifications.

[0046] S41. Establish the current Park transformation transfer relationship of the grid-side converter, including: Based on the Park transformation relationship, the grid-side converter current in the three-phase stationary coordinate system is converted to the dq synchronous rotating coordinate system. The frequency domain transfer relationship is shown in the following equation: (13) in, , These are the small-signal d-axis and q-axis currents of the grid-side converter, respectively. , , , The following are the fifth-order coefficient matrices representing the small-signal transfer relationship of the AC current in the frequency domain of the grid-side converter: (14) , , These are the steady-state current vector matrices of the three phases a, b, and c of the photovoltaic inverter, respectively. The phase sequence matrix of the small signal vector is expressed as follows: . for The conjugate of d.

[0047] , Let cosine and sine steady-state vector matrices be the phase-locked angles, respectively, and their expressions are: (15) (16) S43. Based on the results of S41 and S42, establish the frequency domain small-signal transmission relationship of the d-axis modulation signal of the grid-side converter in the multi-control structure of the doubly fed wind turbine; according to Figure 2 (a) shows a schematic diagram of the grid-side converter control structure of a doubly fed wind turbine. The frequency domain small-signal modulation signals of the d and q axes are established. , The transitive relationship is shown in the following equation: (17) in, , , , , These are the fifth-order small-signal coefficient matrices of the frequency domain modulation signals for the d-axis and q-axis of the grid-side converter, respectively, and their expressions are as follows: (18) (19) in, This represents the impedance of the filter capacitor under small-signal frequency sequences. For the decoupling coefficient of the grid-side converter current controller, , These are the fifth-order matrices for the grid-side current controller and the DC voltage controller, respectively, and their expressions are as follows:

[0048] , These are the fifth-order diagonal matrices for the first to second additional controls, respectively, and their expressions are as follows:

[0049] When there is no first additional control or second additional control, or Simply set it to zero.

[0050] Transfer function for grid-side current PI controller; This is the transfer function for a DC voltage PI controller.

[0051] S43. Establish the modulation signal transmission relationship in the three-phase stationary coordinate system under the multi-control structure of the doubly-fed wind turbine grid-side converter, including: Through Park transform, the frequency domain small signals of the d-axis and q-axis modulation signals of the doubly-fed wind turbine grid-side converter are transformed. , Transforming the transmission relationship to a three-phase stationary coordinate system, the modulation signal transmission relationship in the three-phase stationary coordinate system under the multi-control structure of the doubly-fed wind turbine grid-side converter is established as shown in the following equation: (20) in, , , The fifth-order coefficient matrix of the small-signal model of the modulation signal of the photovoltaic inverter is expressed as follows: (twenty one) in, , These are the steady-state values ​​of the modulation signals on the d-axis and q-axis of the grid-side converter, respectively.

[0052] S45. Based on the power circuit relationship, establish the frequency domain small-signal transmission relationship of the converter port voltage on the grid side of the doubly-fed wind turbine, including: according to Figure 1 The topology shown is used to establish the frequency domain small-signal voltage of the converter port on the grid side of the doubly-fed wind turbine. The transitive relationship is shown in the following equation: (twenty two) in, , These are the fifth-order coefficient matrices of the small-signal voltage frequency domain of the grid-side converter, expressed as follows: (twenty three) in, Represents a fifth-order identity matrix. For PWM gain, This is a fifth-order matrix representing the filter inductor impedance under a small-signal frequency sequence, expressed as: . The steady-state vector matrix of the modulated signal is expressed as:

[0053] in, This is the steady-state modulation signal for the grid-side converter; It is the conjugate of the steady-state modulation signal of the grid-side converter.

[0054] S5. Convert the current of the machine-side converter in the three-phase stationary coordinate system to the dq synchronous rotating coordinate system to obtain the Park transformation transmission relationship of the machine-side converter current; based on the control structure of the machine-side converter, the additional control type, and the Park transformation transmission relationship of the machine-side converter current, establish the sixth small signal transmission relationship in the frequency domain of the d and q axis modulation signals under the multi-control structure of the machine-side converter; convert the sixth small signal transmission relationship to the three-phase stationary coordinate system to obtain the second modulation signal transmission relationship in the three-phase stationary coordinate system of the multi-control structure of the machine-side converter; based on the second modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine, establish the seventh small signal transmission relationship in the frequency domain of the machine-side converter port voltage.

[0055] In one embodiment, step S5 includes steps S51 to S54: S51. Establish the current Park transformation transfer relationship of the machine-side converter, including: Based on the Park transformation relationship, the machine-side converter current in the three-phase stationary coordinate system is converted to the dq synchronous rotating coordinate system. The frequency domain transfer relationship is shown in the following equation: (twenty four) in, , These are the small signals of the d-axis and q-axis currents of the machine-side converter, respectively. , , , The fifth-order coefficient matrix of the small-signal AC current model of the machine-side converter in the frequency domain is expressed as follows: (25) in, , , These are the steady-state current vector matrices of the three phases a, b, and c of the machine-side converter, respectively. The phase sequence matrix of the small signal vector is expressed as follows: . , , , These represent the cosine and sine steady-state vector matrices of phase b and phase c, respectively, representing the phase-locked angle.

[0056] S52. Based on the results of S51, establish the frequency domain small-signal transmission relationship of d-axis modulation signals under the multi-control structure of the generator-side converter of the doubly fed wind turbine; according to Figure 2 (b) shows a schematic diagram of the control structure of the generator-side converter of the doubly fed wind turbine. The frequency domain small-signal modulation signals of the d and q axes are established. , The transitive relationship is shown in the following equation: (26) in, , , , , , , , These are the fifth-order coefficient matrices of the frequency domain small-signal modulated signals of the d-axis and q-axis modulated signals of the machine-side converter, respectively, and their expressions are as follows: (27) (28) in, To turn bad, This represents the decoupling coefficient of the machine-side current loop. The stator-to-rotor turns ratio, , , The active power frequency domain small-signal fifth-order coefficient matrix is... , , The fifth-order coefficient matrix of the reactive power small-signal frequency domain is expressed as follows:

[0057]

[0058] in, and These are the steady-state fundamental frequency components of voltage and current, respectively. For machine-side current controller, , These are the fifth-order matrices for the active and reactive power controllers, respectively, and their expressions are as follows:

[0059]

[0060]

[0061] The fifth-order diagonal matrix for the third additional control is expressed as:

[0062] When there is no third additional control, A fifth-order identity matrix is ​​sufficient.

[0063] S53. Establish the modulation signal transmission relationship in the three-phase stationary coordinate system under the multi-control structure of the doubly-fed wind turbine generator-side converter, including: By using the Park transform, the frequency domain small signals of the d-axis and q-axis modulation signals of the doubly-fed wind turbine generator side converter are transformed. , Transforming the transmission relationship to a three-phase stationary coordinate system, the modulation signal transmission relationship in the three-phase stationary coordinate system under the multi-control structure of the doubly-fed wind turbine generator's machine-side converter is established as shown in the following equation: (29) in, , , , The fifth-order coefficient matrix of the small-signal model of the modulation signal of the machine-side converter is expressed as follows: (30) in, , These are the steady-state values ​​of the d-axis and q-axis modulation signals of the machine-side converter, respectively.

[0064] The fifth-order diagonal matrix for the fourth additional control is expressed as:

[0065] When there is no fourth additional control, Simply set it to zero.

[0066] S54. Based on the power circuit relationship, establish the frequency domain small-signal transmission relationship of the converter port voltage of the doubly-fed wind turbine, including: according to Figure 1 The topology shown is used to establish the frequency domain small-signal voltage at the converter port of the doubly-fed wind turbine. The transitive relationship is shown in the following equation: (31) in, , , , , These are the fifth-order coefficient matrices of the frequency domain small-signal model of the machine-side converter, expressed as follows: (32) in, For PWM gain, This is a fifth-order matrix representing the filter inductor impedance under a small-signal frequency sequence, expressed as: . The steady-state vector matrix of the modulated signal is expressed as:

[0067] in, , These represent the conjugate of the steady-state modulation signal of the machine-side converter and the steady-state modulation signal of the machine-side converter, respectively.

[0068] S6. Solve the system of equations based on the first, second, fifth, and seventh small-signal transmission relationships to obtain the frequency domain admittance model of the doubly fed wind turbine.

[0069] In one embodiment, by combining equations (1), (6), (22), and (31), the frequency domain admittance model of the doubly-fed wind turbine is obtained as shown in the following equation: (33) in, , , , , , Let represent the terminal voltage coefficient matrix, stator current coefficient matrix, current coefficient matrix, generator current coefficient matrix, terminal voltage coefficient matrix, and stator current coefficient matrix of the generator, respectively. Their expressions are: (34) in, This represents the fifth-order coefficient matrix of the small-signal frequency domain of the grid-side converter voltage-DC voltage. This represents the fifth-order coefficient matrix of the small-signal frequency domain of the DC-DC voltage-grid-side converter current. This represents the fifth-order coefficient matrix of the voltage-current frequency domain small-signal converter on the grid side. This represents the fifth-order coefficient matrix of the small-signal current in the frequency domain of the DC-DC voltage-to-machine-side converter; This represents the fifth-order coefficient matrix of the small-signal voltage in the frequency domain of the DC-DC voltage-to-machine-side converter; This represents the fifth-order coefficient matrix of the small-signal voltage in the frequency domain of the DC-to-grid converter. Represents a bit matrix; This represents the fifth-order coefficient matrix of the small-signal frequency domain of the machine-side converter voltage-DC voltage; This represents the fifth-order coefficient matrix of the small-signal frequency domain of the machine-side converter voltage to the grid-side converter current; This represents the fifth-order coefficient matrix of the small-signal frequency domain of the machine-side converter voltage-machine-side converter current; This represents the fifth-order coefficient matrix of the voltage-stator current frequency domain small-signal converter. This represents the fifth-order coefficient matrix of the small-signal frequency domain of the machine-side converter voltage to the grid-side converter voltage.

[0070] S7. Inverse the frequency domain admittance model of the doubly fed wind turbine to obtain the frequency domain impedance model of the doubly fed wind turbine.

[0071] Inverse the frequency domain model of the doubly-fed wind turbine obtained in step S6 to establish the frequency domain impedance model of the doubly-fed wind turbine as follows: (35) The method provided in steps S1 to S7 above differs from existing methods for establishing overall port impedance for specific control structures in impedance modeling of doubly-fed induction generator (DFIG) wind turbines with multiple control structures. This invention categorizes additional controls based on input and output signal types, establishing a universal impedance model under multiple control structures. When the control structure changes, only a few components need to be modified to obtain the new impedance, enhancing the flexibility of the impedance model and improving modeling efficiency.

[0072] To address the issue of high computational complexity in obtaining impedance analytical models, this invention employs a modular modeling method. The impedance acquisition process is modularized, requiring only simple matrix operations throughout the calculation process, significantly reducing modeling complexity and facilitating program implementation.

[0073] It should be noted that the method proposed in this invention is not limited to the additional control described above, and is also applicable to the impedance acquisition of additional control structures for doubly fed wind turbine generators.

[0074] To demonstrate the effectiveness of the embodiments of the present invention, a specific application example is provided, with the doubly fed wind turbine topology as follows: Figure 1 As shown, the control block diagram is as follows: Figure 4 As shown in Table 1, the main circuit parameters are shown in Table 2, and the control parameters are shown in Table 2. A simulation model was built in MATLAB / Simulink software, and the impedance scanning method with perturbation injection was used for verification.

[0075] Table 1 Main Circuit Parameters of Doubly Fed Wind Turbine Units

[0076] Table 2 Control parameters of double-fed wind turbine generators

[0077] The comparison results of impedance measurements obtained based on frequency scanning and impedance analytical values ​​obtained by numerical calculation based on the method proposed in this invention are as follows: Figure 5As shown in the figure, the impedance analytical values ​​obtained by numerical calculation using the method proposed in this invention are represented by solid lines, and the measurement results are represented by discrete points. The comparison results show that the analytical model and the scanning results agree well, verifying the accuracy of the impedance acquisition method of this invention.

[0078] Example 2 like Figure 5 As shown, based on the same inventive concept as the above embodiments, the present invention also provides a universal impedance acquisition device under a multi-control structure for doubly-fed wind turbines, comprising: The identification module is used to determine the additional control type of the doubly fed wind turbine; each additional control is distinguished based on the source of the input signal and the location of the output signal. The first processing module is used to establish the first small signal transmission relationship between the stator and rotor voltages and currents based on the relationship between the stator and rotor voltages and currents of the doubly fed asynchronous generator. The second processing module is used to establish the second small-signal transmission relationship in the DC voltage frequency domain based on the instantaneous power balance relationship between the AC and DC ports. The third processing module is used to establish the third small-signal transmission relationship in the frequency domain of terminal voltage-phase based on the phase-locked loop control structure; to convert the grid-side converter current in the three-phase stationary coordinate system to the dq synchronous rotating coordinate system to obtain the grid-side converter current Park transformation transmission relationship; to establish the fourth small-signal transmission relationship in the frequency domain of d and q axis modulation signals under the multi-control structure of the grid-side converter based on the additional control type, the third small-signal transmission relationship, and the grid-side converter current Park transformation transmission relationship; to convert the fourth small-signal transmission relationship to the three-phase stationary coordinate system to obtain the first modulation signal transmission relationship; and to establish the fifth small-signal transmission relationship in the frequency domain of grid-side converter port voltage based on the first modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine. The fourth processing module is used to convert the machine-side converter current in the three-phase stationary coordinate system to the dq synchronous rotating coordinate system to obtain the machine-side converter current Park transformation transmission relationship; based on the machine-side converter control structure, additional control type, and machine-side converter current Park transformation transmission relationship, it establishes the sixth small-signal transmission relationship in the frequency domain of the d and q axis modulation signals under the multi-control structure of the machine-side converter; it converts the sixth small-signal transmission relationship to the three-phase stationary coordinate system to obtain the second modulation signal transmission relationship in the three-phase stationary coordinate system of the multi-control structure of the machine-side converter; according to the second modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine, it establishes the seventh small-signal transmission relationship in the frequency domain of the machine-side converter port voltage. The first solution module is used to solve the simultaneous solution based on the first small-signal transmission relationship, the second small-signal transmission relationship, the fifth small-signal transmission relationship and the seventh small-signal transmission relationship to obtain the frequency domain admittance model of the doubly fed wind turbine. The second solution module is used to invert the frequency domain admittance model of the doubly fed wind turbine to obtain the frequency domain impedance model of the doubly fed wind turbine.

[0079] In one embodiment, the additional control types include a first additional control, a second additional control, a third additional control, and a fourth additional control; wherein, the first additional control input signal is the d-axis and q-axis capacitor current of the doubly-fed induction generator (DFIG), and the output signal is added to the d-axis and q-axis modulation signal of the grid-side converter; the second additional control input signal is the d-axis and q-axis grid connection point voltage of the DFIG, and the output signal is added to the d-axis and q-axis modulation signal of the grid-side converter; the third additional control input signal is the three-phase AC current of the DFIG on the generator side, and the output signal is added to the a-axis, b-axis, and c-axis modulation signal of the generator side converter; the fourth additional control input signal is the sampled value of the three-phase AC current of the DFIG on the generator side, and the output signal is the feedback value of the three-phase AC current on the generator side.

[0080] In one embodiment, a fourth small-signal transfer relationship in the frequency domain of the d-axis and q-axis modulation signals under the multi-control structure of the grid-side converter is established based on the additional control type, the third small-signal transfer relationship, and the Park transform transfer relationship of the grid-side converter current, including:

[0081]

[0082]

[0083] in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulated signals of the d-axis and q-axis modulated signals of the network-side converter, respectively. It is a small signal in the frequency domain of DC voltage; For small AC terminal voltage signals; This is the small signal of AC current from the grid-side converter; , These are fifth-order matrices for the grid-side current controller and the DC voltage controller, respectively. , These are the fifth-order diagonal matrices representing the first and second additional controls, respectively. When neither the first nor the second additional control is present, [the matrix will be...]. or =0; For the decoupling coefficients of the grid-side converter current controller; , , , These are the fifth-order coefficient matrices representing the frequency domain small-signal propagation relationship of AC current in the grid-side converter; The impedance of the filter capacitor is given under small signal frequency sequences.

[0084] In one embodiment, based on the machine-side converter control structure, additional control type, and machine-side converter current Park transformation transfer relationship, a sixth small-signal transfer relationship in the frequency domain of the d-axis and q-axis modulation signals under the multi-control structure of the machine-side converter is established, including:

[0085]

[0086]

[0087] in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulation signals of the d-axis and q-axis modulated signals of the machine-side converter, respectively. This is the small signal of the stator winding current; This is the small signal of AC current from the grid-side converter; For small AC terminal voltage signals; For worsening; For machine-side current controller, , These are fifth-order matrices for active and reactive power controllers, respectively. This represents the decoupling coefficient of the machine-side current loop. The stator-to-rotor turns ratio, , , These are the fifth-order coefficient matrices of the active power frequency domain small-signal signal, respectively. , , These are the fifth-order coefficient matrices of the small-signal reactive power in the frequency domain; For the third additional control, a fifth-order diagonal matrix is ​​used. When the third additional control is not present, [the matrix is...]. Take a fifth-order identity matrix.

[0088] Example 3 like Figure 6As shown, the present invention also provides an electronic device 100 for implementing a universal impedance acquisition method under a multi-control structure of a doubly fed wind turbine; the electronic device 100 includes a memory 101, at least one processor 102, a computer program 103 stored in the memory 101 and capable of running on at least one processor 102, and at least one communication bus 104.

[0089] The memory 101 can be used to store the computer program 103. The processor 102 implements the steps of the general impedance acquisition method under the multi-control structure of a doubly fed wind turbine in Embodiment 1 by running or executing the computer program stored in the memory 101 and calling the data stored in the memory 101.

[0090] The memory 101 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs required for at least one function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created based on the use of the electronic device 100 (such as audio data), etc. In addition, the memory 101 may include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other non-volatile solid-state storage device.

[0091] At least one processor 102 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Processor 102 may be a microprocessor or any conventional processor. Processor 102 is the control center of electronic device 100, connecting various parts of electronic device 100 via various interfaces and lines.

[0092] The memory 101 in the electronic device 100 stores multiple instructions to implement a universal impedance acquisition method under a multi-control structure for a doubly-fed wind turbine generator. The processor 102 can execute multiple instructions to achieve the following: Determine the additional control type for the doubly fed wind turbine; among which, each additional control is distinguished according to the source of the input signal and the position of the output signal. Based on the relationship between the stator and rotor voltages and currents of a doubly-fed asynchronous generator, establish the first small-signal transmission relationship between the stator and rotor voltages and currents. Based on the instantaneous power balance relationship between AC and DC ports, a second small-signal transmission relationship in the DC voltage frequency domain is established; Based on the phase-locked loop control structure, a third small-signal transmission relationship in the terminal voltage-phase frequency domain is established; the grid-side converter current in the three-phase stationary coordinate system is transformed to the dq synchronous rotating coordinate system to obtain the grid-side converter current Park transformation transmission relationship; based on the additional control type, the third small-signal transmission relationship, and the grid-side converter current Park transformation transmission relationship, a fourth small-signal transmission relationship in the d and q axis modulation signal frequency domain under the multi-control structure of the grid-side converter is established; the fourth small-signal transmission relationship is transformed to the three-phase stationary coordinate system to obtain the first modulation signal transmission relationship; based on the first modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine, a fifth small-signal transmission relationship in the grid-side converter port voltage frequency domain is established. The current of the machine-side converter in the three-phase stationary coordinate system is transformed to the dq synchronous rotating coordinate system to obtain the Park transformation transmission relationship of the machine-side converter current. Based on the control structure, additional control type, and Park transformation transmission relationship of the machine-side converter current, the sixth small-signal transmission relationship of the d and q axis modulation signals in the frequency domain under the multi-control structure of the machine-side converter is established. The sixth small-signal transmission relationship is transformed to the three-phase stationary coordinate system to obtain the second modulation signal transmission relationship in the three-phase stationary coordinate system under the multi-control structure of the machine-side converter. According to the second modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine, the seventh small-signal transmission relationship of the port voltage of the machine-side converter is established in the frequency domain. Based on the first, second, fifth, and seventh small-signal transmission relationships, a simultaneous solution is performed to obtain the frequency domain admittance model of the doubly fed wind turbine. By inverting the frequency domain admittance model of the doubly-fed wind turbine, the frequency domain impedance model of the doubly-fed wind turbine is obtained.

[0093] Example 4 If the modules / units integrated in the electronic device 100 are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, and read-only memory (ROM).

[0094] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0095] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0096] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0097] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0098] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A universal impedance acquisition method for a doubly-fed wind turbine under a multi-control structure, characterized in that, include: Determine the additional control type for the doubly fed wind turbine; among which, each additional control is distinguished according to the source of the input signal and the position of the output signal. Based on the relationship between the stator and rotor voltages and currents of a doubly-fed asynchronous generator, establish the first small-signal transmission relationship between the stator and rotor voltages and currents. Based on the instantaneous power balance relationship between AC and DC ports, a second small-signal transmission relationship in the DC voltage frequency domain is established; Based on the phase-locked loop control structure, a third small-signal transmission relationship in the terminal voltage-phase frequency domain is established; the grid-side converter current in the three-phase stationary coordinate system is transformed to the dq synchronous rotating coordinate system to obtain the grid-side converter current Park transformation transmission relationship; based on the additional control type, the third small-signal transmission relationship, and the grid-side converter current Park transformation transmission relationship, a fourth small-signal transmission relationship in the d and q axis modulation signal frequency domain under the multi-control structure of the grid-side converter is established; the fourth small-signal transmission relationship is transformed to the three-phase stationary coordinate system to obtain the first modulation signal transmission relationship; based on the first modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine, a fifth small-signal transmission relationship in the grid-side converter port voltage frequency domain is established. The current of the machine-side converter in the three-phase stationary coordinate system is transformed to the dq synchronous rotating coordinate system to obtain the Park transformation transmission relationship of the machine-side converter current. Based on the control structure, additional control type, and Park transformation transmission relationship of the machine-side converter current, the sixth small-signal transmission relationship of the d and q axis modulation signals in the frequency domain under the multi-control structure of the machine-side converter is established. The sixth small-signal transmission relationship is transformed to the three-phase stationary coordinate system to obtain the second modulation signal transmission relationship in the three-phase stationary coordinate system under the multi-control structure of the machine-side converter. According to the second modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine, the seventh small-signal transmission relationship of the port voltage of the machine-side converter is established in the frequency domain. Based on the first, second, fifth, and seventh small-signal transmission relationships, a simultaneous solution is performed to obtain the frequency domain admittance model of the doubly fed wind turbine. By inverting the frequency domain admittance model of the doubly-fed wind turbine, the frequency domain impedance model of the doubly-fed wind turbine is obtained.

2. The method according to claim 1, characterized in that, The additional control types include a first additional control, a second additional control, a third additional control, and a fourth additional control. The first additional control input signal is the d-axis and q-axis capacitor current of the doubly-fed induction generator (DFIG), and the output signal is added to the d-axis and q-axis modulation signals of the grid-side converter. The second additional control input signal is the d-axis and q-axis grid-connected point voltage of the DFIG, and the output signal is added to the d-axis and q-axis modulation signals of the grid-side converter. The third additional control input signal is the three-phase AC current on the turbine side of the DFIG, and the output signal is added to the a-axis, b-axis, and c-axis modulation signals of the turbine-side converter. The fourth additional control input signal is the sampled value of the three-phase AC current on the turbine side of the DFIG, and the output signal is the feedback value of the three-phase AC current on the turbine side.

3. The method according to claim 1, characterized in that, Based on the additional control type, the third small-signal transmission relationship, and the Park transform transmission relationship of the grid-side converter current, a fourth small-signal transmission relationship in the frequency domain of the d-axis and q-axis modulation signals under the multi-control structure of the grid-side converter is established, including: in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulated signals of the d-axis and q-axis modulated signals of the network-side converter, respectively. It is a small signal in the frequency domain of DC voltage; For small AC terminal voltage signals; This is the small signal of AC current from the grid-side converter. , These are fifth-order matrices for the grid-side current controller and the DC voltage controller, respectively. , These are the fifth-order diagonal matrices representing the first and second additional controls, respectively. When neither the first nor the second additional control is present, [the matrix will be...]. or =0; For the decoupling coefficients of the grid-side converter current controller; , , , These are the fifth-order coefficient matrices representing the frequency domain small-signal propagation relationship of AC current in the grid-side converter; The impedance of the filter capacitor is given under small signal frequency sequences.

4. The method according to claim 1, characterized in that, Based on the machine-side converter control structure, additional control types, and the Park transform transfer relationship of the machine-side converter current, a sixth small-signal transfer relationship in the frequency domain of the d-axis and q-axis modulated signals under the multi-control structure of the machine-side converter is established, including: in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulation signals of the d-axis and q-axis modulated signals of the machine-side converter, respectively. This is the small signal of the stator winding current; This is the small signal of AC current from the grid-side converter. For small AC terminal voltage signals; For worsening; For machine-side current controller, , These are fifth-order matrices for active and reactive power controllers, respectively; This represents the decoupling coefficient of the machine-side current loop. The stator-to-rotor turns ratio, , , These are the fifth-order coefficient matrices of the active power frequency domain small-signal matrix, , , These are the fifth-order coefficient matrices of the small-signal reactive power in the frequency domain; For the third additional control, a fifth-order diagonal matrix is ​​used. When the third additional control is not present, [the matrix is...]. Take a fifth-order identity matrix.

5. A universal impedance acquisition device for a multi-control structure of a doubly-fed wind turbine, characterized in that, include: The identification module is used to determine the additional control type of the doubly fed wind turbine; each additional control is distinguished based on the source of the input signal and the location of the output signal. The first processing module is used to establish the first small signal transmission relationship between the stator and rotor voltages and currents based on the relationship between the stator and rotor voltages and currents of the doubly fed asynchronous generator. The second processing module is used to establish the second small-signal transmission relationship in the DC voltage frequency domain based on the instantaneous power balance relationship between the AC and DC ports. The third processing module is used to establish the third small-signal transmission relationship in the frequency domain of terminal voltage-phase based on the phase-locked loop control structure; to convert the grid-side converter current in the three-phase stationary coordinate system to the dq synchronous rotating coordinate system to obtain the grid-side converter current Park transformation transmission relationship; to establish the fourth small-signal transmission relationship in the frequency domain of d and q axis modulation signals under the multi-control structure of the grid-side converter based on the additional control type, the third small-signal transmission relationship, and the grid-side converter current Park transformation transmission relationship; to convert the fourth small-signal transmission relationship to the three-phase stationary coordinate system to obtain the first modulation signal transmission relationship; and to establish the fifth small-signal transmission relationship in the frequency domain of grid-side converter port voltage based on the first modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine. The fourth processing module is used to convert the machine-side converter current in the three-phase stationary coordinate system to the dq synchronous rotating coordinate system to obtain the machine-side converter current Park transformation transmission relationship; based on the machine-side converter control structure, additional control type, and machine-side converter current Park transformation transmission relationship, it establishes the sixth small-signal transmission relationship in the frequency domain of the d and q axis modulation signals under the multi-control structure of the machine-side converter; it converts the sixth small-signal transmission relationship to the three-phase stationary coordinate system to obtain the second modulation signal transmission relationship in the three-phase stationary coordinate system of the multi-control structure of the machine-side converter; according to the second modulation signal transmission relationship and the power circuit relationship of the doubly-fed wind turbine, it establishes the seventh small-signal transmission relationship in the frequency domain of the machine-side converter port voltage. The first solution module is used to solve the simultaneous solution based on the first small-signal transmission relationship, the second small-signal transmission relationship, the fifth small-signal transmission relationship and the seventh small-signal transmission relationship to obtain the frequency domain admittance model of the doubly fed wind turbine. The second solution module is used to invert the frequency domain admittance model of the doubly fed wind turbine to obtain the frequency domain impedance model of the doubly fed wind turbine.

6. The apparatus according to claim 5, characterized in that, The additional control types include a first additional control, a second additional control, a third additional control, and a fourth additional control. The first additional control input signal is the d-axis and q-axis capacitor current of the doubly-fed induction generator (DFIG), and the output signal is added to the d-axis and q-axis modulation signals of the grid-side converter. The second additional control input signal is the d-axis and q-axis grid-connected point voltage of the DFIG, and the output signal is added to the d-axis and q-axis modulation signals of the grid-side converter. The third additional control input signal is the three-phase AC current on the turbine side of the DFIG, and the output signal is added to the a-axis, b-axis, and c-axis modulation signals of the turbine-side converter. The fourth additional control input signal is the sampled value of the three-phase AC current on the turbine side of the DFIG, and the output signal is the feedback value of the three-phase AC current on the turbine side.

7. The apparatus according to claim 5, characterized in that, Based on the additional control type, the third small-signal transmission relationship, and the Park transform transmission relationship of the grid-side converter current, a fourth small-signal transmission relationship in the frequency domain of the d-axis and q-axis modulation signals under the multi-control structure of the grid-side converter is established, including: in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulated signals of the d-axis and q-axis modulated signals of the network-side converter, respectively. It is a small signal in the frequency domain of DC voltage; For small AC terminal voltage signals; This is the small signal of AC current from the grid-side converter. , These are fifth-order matrices for the grid-side current controller and the DC voltage controller, respectively. , These are the fifth-order diagonal matrices representing the first and second additional controls, respectively. When neither the first nor the second additional control is present, [the matrix will be...]. or =0; For the decoupling coefficients of the grid-side converter current controller; , , , These are the fifth-order coefficient matrices representing the frequency domain small-signal propagation relationship of AC current in the grid-side converter; The impedance of the filter capacitor is given under small signal frequency sequences.

8. The apparatus according to claim 5, characterized in that, Based on the machine-side converter control structure, additional control types, and the Park transform transfer relationship of the machine-side converter current, a sixth small-signal transfer relationship in the frequency domain of the d-axis and q-axis modulated signals under the multi-control structure of the machine-side converter is established, including: in, , These are the small frequency domain signals of the d-axis and q-axis modulation signals, respectively. , , , , , , , These are the fifth-order coefficient matrices of the small-signal frequency domain modulation signals of the d-axis and q-axis modulated signals of the machine-side converter, respectively. This is the small signal of the stator winding current; This is the small signal of AC current from the grid-side converter. For small AC terminal voltage signals; For worsening; For machine-side current controller, , These are fifth-order matrices for active and reactive power controllers, respectively; This represents the decoupling coefficient of the machine-side current loop. The stator-to-rotor turns ratio, , , These are the fifth-order coefficient matrices of the active power frequency domain small-signal matrix, , , These are the fifth-order coefficient matrices of the small-signal reactive power in the frequency domain; For the third additional control, a fifth-order diagonal matrix is ​​used. When the third additional control is not present, [the matrix is...]. Take a fifth-order identity matrix.

9. An electronic device, characterized in that, It includes a processor and a memory, the processor being configured to execute a computer program stored in the memory to implement the method as described in any one of claims 1 to 4.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one instruction that, when executed by a processor, implements the method as described in any one of claims 1 to 4.

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