Control strategy comparative analysis method and system of doubly-fed fan, terminal and medium

Abstract

The invention relates to the technical field of wind power, and particularly provides a control strategy comparative analysis method and system of a doubly-fed fan, a terminal and a medium. Comprising the following steps: constructing a double-fed fan system adopting VM-DPC and obtaining a first electrical parameter and a first operation state variable, constructing a double-fed fan system adopting VOC and obtaining a second electrical parameter and a second operation state variable; constructing a unified power transfer function of an RSC side based on the power control transfer function of the RSC adopting the VM-DPC and the power control transfer function of the RSC adopting the VOC; constructing a unified power transfer function of the GSC side based on the power control transfer function of the GSC adopting the VM-DPC and the power control transfer function of the GSC adopting the VOC; and complex vector comprehensive impedance of the double-fed fan based on the VM-DPC and the complex vector comprehensive impedance of the double-fed fan based on the VOC are obtained respectively, and contrastive analysis is carried out on the complex vector comprehensive impedance. And the accuracy of an analysis comparison result is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power, and particularly relates to a method, system, terminal and medium for comparative analysis of control strategies of doubly-fed wind turbines. Background Art

[0002] Doubly-fed wind turbines are a common type of wind power generation equipment. By analyzing the impedance characteristics of doubly-fed wind turbines, the stability of wind power grid connection can be effectively evaluated. Since the dynamic characteristics of doubly-fed wind turbines are mainly dominated by their control strategies, different control strategies will significantly affect their impedance characteristics. The commonly used control strategies mainly include voltage-oriented vector control and direct power control.

[0003] Among various types of direct power control, one type of voltage modulation direct power control proposed for voltage source converters αβ in a coordinate system has attracted wide attention. This control does not require a phase-locked loop and has the advantage of small steady-state harmonics due to the use of pulse width modulation with a fixed switching frequency. Existing patents have extended it to the control of doubly-fed wind turbines and verified its superior steady-state and transient performance through comparison with typical voltage-oriented vector control.

[0004] However, when existing patents compare voltage modulation direct power control with voltage-oriented vector control, the parameters of both controls are randomly selected. In fact, the structures of the two controls are different, and the parameter selection principles are also different. Therefore, directly comparing the two controls cannot ensure that their dynamic characteristics have a unified benchmark, and it is difficult to guarantee the accuracy of the analysis and comparison results. Summary of the Invention

[0005] Aiming at the above deficiencies of the prior art, the present invention provides a method, system, terminal and medium for comparative analysis of control strategies of doubly-fed wind turbines to solve the above technical problems.

[0006] In a first aspect, the present invention provides a method for comparative analysis of control strategies of doubly-fed wind turbines, including: Based on an induction generator, an RSC, and a GSC, respectively, a doubly-fed wind turbine system using VM-DPC is constructed to obtain first electrical parameters and first operating state variables, and a doubly-fed wind turbine system using VOC is constructed to obtain second electrical parameters and second operating state variables; Based on the first electrical parameters and the first operating state variables, a power control transfer function of the RSC using VM-DPC is obtained; based on the second electrical parameters and the second operating state variables, a power control transfer function of the RSC using VOC is obtained; based on the power control transfer function of the RSC using VM-DPC and the power control transfer function of the RSC using VOC, a unified power transfer function on the RSC side is constructed; Obtain the power control transfer function of the GSC using VM-DPC based on the first electrical parameter and the first operating state variable; obtain the power control transfer function of the GSC using VOC based on the second electrical parameter and the second operating state variable; when the voltage control outer loop is not considered, construct the unified power transfer function on the GSC side based on the power control transfer function of the GSC using VM-DPC and the power control transfer function of the GSC using VOC; Define the control parameters of VM-DPC and VOC based on the unified power transfer function on the RSC side and the unified power transfer function on the GSC side, respectively obtain the complex vector comprehensive impedance of the doubly-fed wind turbine based on VM-DPC and the doubly-fed wind turbine based on VOC in combination with the control parameters, and conduct a comparative analysis on the complex vector comprehensive impedance.

[0007] In an optional implementation manner, obtaining the power control transfer function of the RSC using VM-DPC based on the first electrical parameter and the first operating state variable specifically includes: Obtain the stator power, stator voltage equation, and rotor voltage equation based on the first electrical parameter and the first operating state variable. The stator voltage equation includes the stator resistance and stator flux linkage, and the rotor voltage equation includes the rotor resistance and rotor flux linkage; Obtain the stator flux linkage calculation equation and rotor flux linkage calculation equation based on the first electrical parameter and the first operating state variable. The stator flux linkage calculation equation includes the stator inductance, stator current, and rotor current, and the rotor flux linkage calculation equation includes the rotor inductance, stator current, and rotor current to calculate the rotor flux linkage; Substitute the calculated stator flux linkage calculation equation, rotor flux linkage calculation equation, stator voltage equation, and rotor voltage equation into the stator power to obtain the control equation of VM-DPC of the RSC; Obtain the active control and reactive control voltage modulation variables of VM-DPC on the RSC side based on the control equation of VM-DPC of the RSC, establish a linear relationship between the voltage modulation variable and the stator power, and obtain the reference value of the voltage modulation variable based on the linear relationship and the preset reference value of the stator power; Perform Laplace transform on the control equation of VM-DPC of the RSC and substitute the reference value of the voltage modulation variable to obtain the power control transfer function of the RSC using VM-DPC.

[0008] In an optional implementation manner, obtaining the power control transfer function of the RSC using VOC based on the second electrical parameter and the second operating state variable specifically includes: Transform the stator flux linkage calculation equation, rotor flux linkage calculation equation, stator voltage equation, and rotor voltage equation to dq In the coordinate system, and obtain the relationship between the rotor voltage and the rotor current, and the relationship between the stator power and the rotor current; Obtain the rotor current reference value of VOC on the RSC side based on the stator power reference value on the RSC side and the characteristics of the coordinate system; Combine the relationship between the rotor voltage and the rotor current, the relationship between the stator power and the rotor current, and the stator power reference value of VOC on the RSC side to obtain the power control transfer function of the RSC using VOC.

[0009] In an optional embodiment, the power control transfer function of the RSC using VM-PC is specifically:

[0010] The power control transfer function of the RSC using VOC is specifically:

[0011] Wherein, is the stator active power, is the stator active power reference value, is the stator reactive power, is the stator reactive power reference value, is the actual value of the rotor current on the q axis, is the reference value of the rotor current on the q axis, and are the PI parameters of VM-DPC on the RSC side, is the Laplace operator, is the stator resistance, is the rotor inductance, is the excitation inductance, and are the PI parameters of VOC on the RSC side, is the rotor resistance, is the stator inductance; Since the stator resistance in the doubly-fed wind turbine is approximately equal to the rotor resistance and the stator inductance is approximately equal to the rotor inductance, the unified power transfer function on the RSC side constructed based on the power control transfer function of the RSC using VM-DPC and the power control transfer function of the RSC using VOC is specifically:

[0012] Wherein, =( R s + R r ) / 2, =( L s + L r ) / 2.

[0013] In an optional embodiment, obtaining the power control transfer function of the GSC adopting VM-DPC based on the first electrical parameter and the first operating state variable specifically includes: Obtaining the relationships between the GSC output power, the GSC voltage, the GSC current, and the stator voltage based on the first electrical parameter and the first operating state variable; Combining the relationships between the GSC output power, the GSC voltage, the GSC current, and the stator voltage to obtain the control equation of the VM-DPC of the GSC; Based on the control equation of the VM-DPC of the GSC, obtaining the nonlinear active control and reactive control voltage modulation variables, establishing a linear relationship between the voltage modulation variables and the GSC output power, and obtaining the reference value of the voltage modulation variables based on the linear relationship and the preset GSC output power reference value; Performing Laplace transform on the control equation of the VM-DPC of the GSC and substituting the reference value of the voltage modulation variables to obtain the power control transfer function of the GSC adopting VM-DPC.

[0014] In an optional embodiment, obtaining the power control transfer function of the GSC adopting VOC based on the second electrical parameter and the second operating state variable. The ultimate goals of VM-DPC and VOC are both to achieve the control of active power and reactive power. When not considering the voltage outer loop, VM-DPC realizes power control by determining the linear relationship between the voltage modulation variables and the GSC power, and VOC indirectly realizes power control by converting the GSC power reference value into a current reference value and controlling through the current inner loop. The two are approximately equivalent in the power control transfer path. Therefore, constructing the unified power transfer function on the GSC side based on the power control transfer function of the GSC adopting VM-DPC and the power control transfer function of the GSC adopting VOC is specifically:

[0015] where, is the GSC output active power, is the reference value of the GSC active power, is the GSC output reactive power, is the reference value of the GSC reactive power, and are the PI parameters of the current loop of VM-DPC or VOC on the GSC side, is the resistance of the GSC filter, is the inductance of the GSC filter, is the Laplace operator.

[0016] In an alternative embodiment, the comparative analysis of the complex vector comprehensive impedance specifically includes: performing comparative analysis on the amplitude-frequency and phase-frequency characteristics, the main diagonal elements, and the non-main diagonal elements of the two complex vector comprehensive impedances respectively.

[0017] In a second aspect, the present invention provides a comparative analysis system for the control strategies of a doubly-fed wind turbine. When the system is implemented, it executes the above-mentioned comparative analysis method for the control strategies of the doubly-fed wind turbine. The system includes: A system construction module that respectively constructs a doubly-fed wind turbine system using VM-DPC based on an induction generator, an RSC, and a GSC, and obtains first electrical parameters and first operating state variables; constructs a doubly-fed wind turbine system using VOC and obtains second electrical parameters and second operating state variables; An RSC unified power transfer function calculation module that obtains the power control transfer function of the RSC using VM-DPC based on the first electrical parameters and the first operating state variables; obtains the power control transfer function of the RSC using VOC based on the second electrical parameters and the second operating state variables; constructs a unified power transfer function on the RSC side based on the power control transfer function of the RSC using VM-DPC and the power control transfer function of the RSC using VOC; A GSC unified power transfer function calculation module that obtains the power control transfer function of the GSC using VM-DPC based on the first electrical parameters and the first operating state variables; obtains the power control transfer function of the GSC using VOC based on the second electrical parameters and the second operating state variables; when not considering the voltage control outer loop, constructs a unified power transfer function on the GSC side based on the power control transfer function of the GSC using VM-DPC and the power control transfer function of the GSC using VOC; A comparative analysis module that defines the control parameters of VM-DPC and VOC based on the unified power transfer function on the RSC side and the unified power transfer function on the GSC side, respectively obtains the complex vector comprehensive impedance of the doubly-fed wind turbine based on VM-DPC and the doubly-fed wind turbine based on VOC in combination with the control parameters, and performs a comparative analysis on the complex vector comprehensive impedance.

[0018] In a third aspect, a terminal is provided, including: A processor and a memory, where The memory is used to store a computer program, The processor is used to call and run the computer program from the memory, so that the terminal executes the above-mentioned method of the terminal.

[0019] In a fourth aspect, a computer-readable storage medium is provided. Instructions are stored in the computer-readable storage medium, and when they run on a computer, the computer is made to execute the methods described in the above aspects.

[0020] The beneficial effects of the present invention are as follows. The method, system, terminal and medium for comparative analysis of the control strategy of a doubly-fed fan provided by the present invention respectively construct a doubly-fed fan system with VM-DPC and VOC, obtain relevant parameters and variables, and then obtain the power control transfer functions of the RSC and GSC under the two control methods, construct a unified power transfer function, define control parameters based on this, and obtain the complex vector comprehensive impedance for comparative analysis. This helps to deeply understand the electrical characteristics and performance differences of the doubly-fed fan under the two control strategies, provides a theoretical basis and analysis method for optimizing the control of the doubly-fed fan system, improving the system stability and operation efficiency, and improves the accuracy of the analysis and comparison results.

[0021] In addition, the design principle of the present invention is reliable, the structure is simple, and it has a very wide application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 is a schematic flowchart of a method for comparative analysis of the control strategy of a doubly-fed fan according to an embodiment of the present invention.

[0024] Figure 2 is a structure diagram of a DFIG based on VM-DPC according to an embodiment of the present invention.

[0025] Figure 3 is a VOC structure diagram of a DFIG according to an embodiment of the present invention.

[0026] Figure 4 is a comparison result of the DFIG impedance based on VM-DPC and based on VOC according to an embodiment of the present invention.

[0027] Figure 5(a) is the eigenvalue trajectory when the SCR decreases from 3 to 1.9 under VM-DPC according to an embodiment of the present invention.

[0028] Figure 5(b) is the eigenvalue trajectory when the SCR decreases from 3 to 1.9 under VOC according to an embodiment of the present invention.

[0029] Figure 6 is a comparison result of the power step response of DFIGs based on VM-DPC and based on VOC according to an embodiment of the present invention; (a) k p,rsc = k p,ir = 315, k i,rsc= k i,ir =5800; (b) k p,rsc = k p,ir =630, k i,rsc = k i,ir =11600。

[0030] Figure 7 is the simulation result of the DFIG based on VM-DPC in an embodiment of the present invention.

[0031] FIG. 8(a) is a waveform diagram of the simulation result of the DFIG based on VOC in an embodiment of the present invention.

[0032] FIG. 8(b) is the FFT of the simulation result of the DFIG based on VOC in an embodiment of the present invention.

[0033] Figure 9 is a schematic block diagram of a control strategy comparison and analysis system for a doubly-fed wind turbine in an embodiment of the present invention.

[0034] Figure 10 is a schematic structural diagram of a terminal provided in an embodiment of the present invention. Detailed implementation manners

[0035] In order to enable those skilled in the art of the present technology to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention.

[0037] The control strategy comparison and analysis method for a doubly-fed wind turbine provided in the embodiments of the present invention is executed by a computer device. Correspondingly, the control strategy comparison and analysis system for a doubly-fed wind turbine runs in the computer device.

[0038] Figure 1 is a schematic flowchart of the control strategy comparison and analysis method for a doubly-fed wind turbine in an embodiment of the present invention. Among them, Figure 1The executing entity can be a comparative analysis system for the control strategies of a doubly-fed wind turbine. According to different requirements, the order of the steps in this flowchart can be changed, and some can be omitted.

[0039] As Figure 1 shown, the method includes: S1, respectively construct a doubly-fed wind turbine system using VM-DPC based on an induction generator, RSC, and GSC, and obtain the first electrical parameters and the first operating state variables; construct a doubly-fed wind turbine system using VOC and obtain the second electrical parameters and the second operating state variables; Build a hardware platform including an induction generator, RSC, and GSC. When constructing a doubly-fed system using VM-DPC, use sensors to detect information such as stator power, rotor voltage and current, and control the RSC according to the algorithm to maintain the DC bus voltage of the GSC, etc.; when constructing a doubly-fed system using VOC, control the current components of the RSC and GSC after voltage-current coordinate transformation, and also obtain parameters and variables through sensors, so as to obtain the electrical parameters and operating state variables of the two systems respectively.

[0040] The acquisition of the first electrical parameters and the first operating state variables, as well as the second electrical parameters and the second operating state variables, helps to deeply understand the electrical characteristics and operating states of the two systems, and provides a detailed basis for comparing and analyzing the performance differences of the two control strategies.

[0041] S2, obtain the power control transfer function of the RSC using VM-DPC based on the first electrical parameters and the first operating state variables; obtain the power control transfer function of the RSC using VOC based on the second electrical parameters and the second operating state variables; construct a unified power transfer function on the RSC side based on the power control transfer function of the RSC using VM-DPC and the power control transfer function of the RSC using VOC; Based on the obtained parameters and variables of the VM-DPC system, start from the relationship between power deviation and voltage vector to deduce the power control transfer function of the RSC; for the VOC system, start from the relationship between current and power and combine the control strategy to deduce its RSC transfer function, and then construct a unified power transfer function on the RSC side through analysis and processing.

[0042] Precisely establish the mathematical model of the RSC power control under the two control strategies, and clearly express the dynamic relationship between the input (such as power reference value, etc.) and the output (such as actual power, etc.) in the form of a transfer function.

[0043] S3. Obtain the power control transfer function of the GSC using VM-DPC based on the first electrical parameter and the first operating state variable; obtain the power control transfer function of the GSC using VOC based on the second electrical parameter and the second operating state variable; when not considering the voltage control outer loop, construct the unified power transfer function on the GSC side based on the power control transfer function of the GSC using VM-DPC and the power control transfer function of the GSC using VOC. Based on the parameters and variables of the VM-DPC system, analyze the working principle and control objectives of the GSC, and deduce its power control transfer function through circuit equations, power equations, etc. When not considering the voltage outer loop, simplify and refine to construct the unified power transfer function on the GSC side.

[0044] The unified power transfer function on the GSC side obtained in this way can focus more on the essence and core part of power control without considering the voltage control outer loop, reducing unnecessary complexity.

[0045] S4. Define the control parameters of VM-DPC and VOC based on the unified power transfer function on the RSC side and the unified power transfer function on the GSC side, respectively obtain the complex vector comprehensive impedance of the doubly-fed wind turbine based on VM-DPC and the doubly-fed wind turbine based on VOC in combination with the control parameters, and conduct a comparative analysis on the complex vector comprehensive impedance.

[0046] Define the control parameters according to the unified power transfer function on the RSC and GSC sides, substitute them into the doubly-fed wind turbine model, and use the complex vector analysis method to respectively obtain the complex vector comprehensive impedance under the two control strategies, and then conduct a comparative analysis on their amplitude, phase, frequency characteristics, etc.

[0047] The acquisition and comparative analysis of the complex vector comprehensive impedance provide an important basis for evaluating the stability, harmonic characteristics, and interaction characteristics with the power grid of the system.

[0048] Optionally, as an embodiment of the present invention, the detailed topological structure of a doubly-fed induction generator (DFIG) based on voltage-modulated direct power control (VM-DPC) is as Figure 2 shown. Among them u s and u r are the stator and rotor voltages respectively, i s and i r are the stator and rotor currents respectively, u g and ig are the GSC voltage and current respectively, i t is the total current at the point of common coupling (PCC) of the DFIG, u dc is the DC bus voltage. Unless otherwise specified, bold variables represent αβ complex vectors in the coordinate system. For example, u s = u sα +j u sβ . By applying VM-DPC, the rotor-side converter (RSC) is responsible for modulating the stator power, while the grid-side converter (GSC) controls the DC voltage.

[0049] Optionally, as an embodiment of the present invention, the vector-oriented control (VOC) structure of the DFIG is as Figure 3 shown. The RSC uses current PI modulation to achieve open-loop control of the stator power. The GSC adopts a double-loop control structure with an outer voltage loop and an inner current loop, where k PQ =2 / 3 U sd is the voltage control gain.

[0050] Optionally, as an embodiment of the present invention, specifically obtaining the power control transfer function of the RSC using VM-DPC based on the first electrical parameter and the first operating state variable in step S2 includes: VM-DPC directly decouples and controls the converter output power based on a predefined voltage modulation variable in the stator αβ coordinate system, and then generates the converter voltage command value. For RSC control, since its control object is the stator power, it is necessary to deduce the dynamic relationship between the stator power and the rotor voltage output by the RSC to construct the control equation of the RSC's VM-DPC.

[0051] The stator active P s and reactive Q s in the αβ coordinate system can be written as: (1) To eliminate the stator current in the stator power, in the αβThe stator and rotor voltage equations of the DFIG main circuit are established in the coordinate system and are expressed as follows: (2) Where ω m is the rotor speed, R s and R r are the stator and rotor resistances respectively. The stator flux linkage ψ s and the rotor flux linkage ψ r can be calculated from the stator and rotor currents as follows: (3) Where L s and L r are the stator and rotor inductances respectively, L m is the excitation inductance.

[0052] Therefore, by differentiating the stator power (1) and substituting (2) and (3), the control equation of the VM-DPC of the RSC can be finally obtained: (4) Where σ αβ = 1 - L s L r / L m L m is the leakage inductance coefficient of the VM-DPC, ω s represents the grid fundamental angular frequency. The relationship between the rotor voltage and current angular frequencies ω r and ω m is ω r = ω s - ω m .

[0053] In the above formula, u rP and u rQThey are respectively defined as the active power control and reactive power control voltage modulation variables of the RSC-side VM-DPC, which have a non-linear relationship with the stator and rotor voltages. By defining the voltage modulation variables, an approximate linear relationship between them and the stator output power can be established, expressed as: (5) Where k s =-2 σ αβ L m / 3 is the VM-DPC gain of the RSC. In a large-capacity doubly-fed wind turbine system, R r is usually relatively small and has little impact on the control performance. Therefore, the compensation terms C rP and C rQ representing the coupling between the stator voltage and rotor current can be ignored.

[0054] Therefore, for a given stator power reference value, by setting the decoupling terms k s ω r Q s and k s ω r P s , and then using PI modulation to control the active and reactive powers to generate u rP and u rQ reference values. Finally, according to the definition of the voltage modulation variable in (4), the voltage modulation transformation equation (6) is deduced inversely to calculate the rotor voltage command value in the αβ coordinate system. The implementation of the above control principle of the RSC-side VM-DPC is as shown in the left blue box in Figure 2 .

[0055] (6) Therefore, according to Figure 2 , the reference value of the RSC-side voltage modulation variable can be expressed in the frequency domain as: (7) Where k p,rsc and k i,rsc are the PI parameters of the RSC-side VM-DPC.

[0056] Perform Laplace transform on (4) and substitute it into (7) for replacement u rP and u rQ , then the power control transfer function of the RSC adopting VM-DPC can be obtained as follows: (8).

[0057] Optionally, as an embodiment of the present invention, in step 2, obtaining the power control transfer function of the RSC adopting VOC based on the second electrical parameter and the second operating state variable specifically includes: The VOC of the RSC is synchronized with the grid voltage based on the PLL, and current control is performed in the dq coordinate system. For this purpose, it is necessary to transform the stator and rotor voltage equations and flux linkage equations of the DFIG main circuit to the dq coordinate system, and the relationship between the rotor voltage and the rotor current is derived as: (9) where σ = 1 - L m L m / L s L r is the leakage inductance coefficient of the VOC. dq The definition method of variables in the αβ coordinate system is the same as that of variables in the u sdq coordinate system except that it has the subscript "dq". For example, u sd = u sq . Furthermore, the RSC current control designed therefrom has the following expression: Figure 3 as shown in (10) where k p,ir and k i,ir are the PI parameters of the VOC on the RSC side.

[0058] Furthermore, in the dq coordinate system, the relationship between the stator power and the rotor current is as follows: (11) Through the above relationship, the rotor current d axis and q axis component reference values can be calculated according to the given stator power reference value.

[0059] Therefore, substituting (10) into (9) and combining with (11), the power control transfer function of the RSC using VOC can be established: (12) It should be noted that according to (11), the stator active power is proportional to the d axial component of the rotor current. The active power control transfer function can be directly established. However, although the stator reactive power has a linear relationship with the q axial component of the rotor current, due to the existence of component 3 u sd u sd / 2 ω s L s , it is impossible to directly derive the reactive power control transfer function. Therefore, (12) only gives the control transfer function of the q axial component of the rotor current, which can approximately reflect the dynamic characteristics of the RSC reactive power control.

[0060] Optionally, as an embodiment of the present invention, the specific construction of the unified power transfer function on the RSC side in step S2 is as follows: Observing (8) and (12), it can be found that the power transfer functions of the two controls have the same form, and the difference lies only in the s linear term coefficient in the denominator. However, in the DFIG, the resistances or inductances of the stator and rotor are extremely close, R s L r and R r L s have little difference in numerical values. Therefore, the average values of the resistances and inductances of the stator and rotor can be used to define the unified power transfer function of VM-DPC and VOC on the RSC side: (13) where =( R s + R r ) / 2, =( L s + L r ) / 2. According to the unified power transfer function of VM-DPC and VOC on the RSC side, as long as the PI parameters are kept consistent, it can ensure that the two controls have the same stator power control dynamic characteristics under ideal grid conditions.

[0061] Optionally, as an embodiment of the present invention, step S3 specifically includes: For GSC control, in the control outer loop of the GSC using VM-DPC, PI modulation is adopted to maintain the DC bus voltage constant, while in the control inner loop, the converter output power is controlled by VM-DPC according to the GSC power reference value generated by the DC voltage outer loop. Therefore, the control equation of VM-DPC for GSC is the dynamic relationship between the GSC output power and the GSC voltage.

[0062] αβ The active power output by the GSC in the coordinate system P g and reactive power Q g can be expressed as: (14) Meanwhile, according to the GSC filter circuit, the relationship between the GSC voltage, the GSC current, and the stator voltage can be obtained as: (15) Where R g and L g are the resistance and inductance of the GSC filter.

[0063] Referring to the derivation process of the RSC side control equation, taking the differential of (14) and substituting (15) to eliminate the GSC current, the control equation of VM-DPC for GSC can be obtained: (16) Similarly, in (16), u gP and u gQ are the nonlinear active power control and reactive power control voltage modulation variables of VM-DPC on the GSC side, respectively. And the linear relationship between the GSC output power and the voltage modulation variables is: (17) Where k g = 2 L g / 3 is the VM-DPC gain of the GSC.

[0064] Therefore, for the GSC output power reference value given by the DC voltage control outer loop, active and reactive power control can also be achieved by PI modulation. Then, by setting the decoupling terms k g ω s Q g andk g ω s P g Generate u gP And u gQ The reference value. Finally, according to the voltage modulation transformation equation (18) on the GSC side, the αβ GSC voltage command value in the coordinate system is calculated. The VM-DPC structure corresponding to the above GSC control principle is as shown in the Figure 2 right blue box in the figure.

[0065] (18) The converters adopting VM-DPC or VOC without the outer voltage control loop have the same power control transfer function. Therefore, the unified power transfer function of VM-DPC and VOC on the GSC side can be directly defined as: (19) Where k p,gsc And k i,gsc Are the PI parameters of the current loop of VM-DPC or VOC on the GSC side. Therefore, by adopting the same control parameters and the outer voltage control loop, the unity of the two control dynamic characteristics of the GSC can be ensured.

[0066] When the outer voltage control loop is not included, the converters adopting VM-DPC or VOC have the same power control transfer function because there are commonalities in the basic principles and circuit structures of their internal power control. During the power control process, both construct control logics around the relationship between the converter output power and related electrical quantities. For VM-DPC, by αβ decoupling the converter output power based on the predefined voltage modulation variable in the stator dq coordinate system, the core lies in deriving the control equation based on the dynamic relationship between the stator power and the rotor voltage, and further determining the approximate linear relationship between the voltage modulation variable and the stator output power to achieve power control. Although VOC has different control methods, such as the GSC adopts current PI modulation and is synchronized with the grid voltage based on PLL for

[0067] GSC power control in the VM-DPC realizes power control in the αβ coordinate system, and derives the Figure 2 complex vector comprehensive impedance of the DFIG based on VM-DPC considering mechanical and GSC dynamics as shown Z DPC . At the same time, based on the Figure 3 DFIG of the VOC shown, the complex vector impedance in the αβ coordinate system can be established as Z VOC . When analyzing the impedance characteristics of the DFIG, the influence of the grid impedance is not considered temporarily, and it is assumed that both DFIGs are directly connected to the grid. The basic parameters of the DFIG are shown in Table 1. The control parameters of VM-DPC and VOC are designed according to the defined unified transfer function to make the power tracking dynamic characteristics of the two controls consistent. The wind speed V w is 12 m / s, and the total active P t and total reactive Q t powers output by the DFIG are 1.5 MW and 0 Mvar respectively.

[0068] Table 1 DFIG parameters

[0069] Under the condition that the power control dynamic characteristics of the DFIGs based on VM-DPC and VOC are consistent, the comparison results of the DFIG impedances corresponding to the two controls are as shown Figure 4 . It can be seen from the figure that the two impedances have similar amplitude-frequency and phase-frequency variation laws near 50 Hz and are also strongly nonlinear. Then, further analysis is carried out from the overall perspective of the full frequency band. For the main diagonal elements of the DFIG impedance, the DFIG based on VM-DPC has a smaller amplitude. And the frequency range in which the main diagonal elements of the DFIG impedance based on VM-DPC show negative resistance characteristics is also narrower. This indicates that under the unified power control dynamic characteristics, the DFIG based on VM-DPC is more stable than the DFIG based on VOC. For the non-main diagonal elements of the DFIG impedance, in the frequency band below 100 Hz, the DFIG based on VOC has a larger amplitude, representing a more significant frequency coupling phenomenon. And in the frequency band above 100 Hz, the frequency coupling phenomenon of the DFIG based on VM-DPC is more significant.

[0070] Optionally, as an embodiment of the present invention, the stability of the DFIGs based on VM-DPC and VOC is compared considering the grid impedance under different grid strengths. The grid side adopts an RL equivalent circuit, and its αβ coordinate system impedance can be expressed as Z grid。Aggregate impedance Z agDPC = Z DPC + Z grid or Z agVOC = Z VOC + Z grid The determinant zeros of are equivalent to the eigenvalues of the DFIG grid-connected system. Therefore, by calculating Z agDPC or Z agVOC whether all the determinant zeros are located in the left half s plane, the small-signal stability of the DFIG grid-connected system can be evaluated. αβ For the th k of the aggregate impedance in the coordinate system, the real parts of the determinant zeros are the same, and the imaginary parts are symmetric about ω s and can be denoted as λ 2k-1 = σ k +j ω k and λ 2k = σ k +j(2 ω s- ω k ). The imaginary parts ω k and 2 ω s- ω k also represent the oscillation frequencies of the oscillation modes corresponding to this pair of zeros in the αβ coordinate system, reflecting the frequency coupling.

[0071] The basic parameters of the DFIG using VM-DPC or VOC still refer to Table 1. Ensure that the PI parameters of the two controls are the same, and compare the grid connection stability of DFIGs based on VM-DPC and VOC under the condition of having the same power control dynamic characteristics. Similarly, when the wind speed is 12 m / s, the active and reactive powers output by the DFIG are 1.5 MW and 0 Mvar respectively. Change the grid impedance to make the grid short-circuit ratio (SCR) drop from 3 to 1.9. Calculate the determinant zeros of the aggregate impedance for the DFIG comprehensive impedance based on the two controls in turn. Then analyze the variation of the system eigenvalues with the grid short-circuit ratio. According to the distance of the eigenvalues from the imaginary axis, λ 1,2 ,λ 3,4 , λ 5 is the dominant eigenvalue of the system. The dominant eigenvalues of the DFIG grid-connected system based on VM-DPC and based on VOC λ 1,2 , λ 3,4 , λ The change trajectories of 5 are shown in Fig. 5(a) and Fig. 5(b) respectively. It can be seen from the figure that as the grid short-circuit ratio decreases, whether using VM-DPC or VOC, the dominant eigenvalues gradually move towards the imaginary axis. However, the eigenvalues corresponding to VOC λ 1,2 will first cross the imaginary axis and reach the right half-plane, while at this time the eigenvalues corresponding to VM-DPC still remain in the left half s plane. When the short-circuit ratio is 2.3, for VOC, λ 1 = 0.003 + j297.47, λ 2 = 0.003 + j330.85. This shows that as the grid short-circuit ratio decreases, the grid strength weakens, and the stability of the DFIG grid-connected system based on VOC gradually weakens until it becomes unstable. While the DFIG based on VM-DPC can maintain stability under the same grid strength. It is proved that under the condition of the same power control dynamic characteristics, the DFIG based on VM-DPC has stronger anti-small disturbance ability than the DFIG based on VOC in a weak grid situation. This is consistent with the comparison conclusion of the DFIG impedances corresponding to the two controls in Section 2.

[0072] Optionally, as an embodiment of the present invention, the power tracking characteristics of DFIGs based on VM-DPC and based on VOC will be analyzed by a step of the given power reference value under ideal grid conditions to verify the correctness of the unified transfer function. At the same time, the stability comparison results of DFIGs based on VM-DPC and based on VOC under different grid strengths are verified by simulation. These simulation verifications are all based on the DFIG simulation model built in MATLAB / Simulink. The basic parameters of the DFIG refer to Table 1. The wind speed is 12 m / s, and the total active power and total reactive power output by the DFIG are 1.5 MW and 0 Mvar respectively.

[0073] The power tracking dynamic characteristics of DFIGs based on VM-DPC and VOC are compared through MATLAB / Simulink simulation. In this example, the grid impedance is not considered and the grid voltage is kept constant, which is an ideal grid condition. The PI parameters of the two controls are kept consistent according to the unified power transfer function. At the initial state of the simulation, the total active power and total reactive power of the DFIGs under the two controls are both set to 0. At the 10th second, the total active power reference values of the DFIGs based on the two controls step to 1.5 MW simultaneously. The simulation results under the two sets of RSC control parameters are as shown in Figure 6 (a) and (b) in the figure. It can be seen from the figure that as long as the PI parameters of the two controls are kept consistent, the DFIGs under the two controls can have the same power tracking characteristics under ideal grid conditions. Thus, the effectiveness of the proposed unified power transfer function is verified.

[0074] The stability comparison results of the DFIG grid-connected systems corresponding to the above two controls are verified through simulation. At the initial state of the simulation, the grid short-circuit ratio is set to 2.5, and the system operates stably at this time. During the simulation process, the grid short-circuit ratio decreases to 2.4 at the 11th second and continues to decrease to 2.3 at the 15th second. The simulation results of the DFIG grid-connected systems based on VM-DPC and VOC are respectively as shown in Figure 7 and Figure 8(a) 、 8(b) shown in the figure. It can be seen from the figure that when the grid short-circuit ratio decreases to 2.4, the systems corresponding to the two controls can both remain stable. When the grid short-circuit ratio continues to decrease to 2.3, the DFIG grid-connected system based on VM-DPC can remain stable, while the DFIG grid-connected system based on VOC shows oscillations and gradually diverges. This is consistent with the change of the dominant eigenvalues of the system shown in Figure 5. Moreover, through FFT calculation, the oscillation frequencies corresponding to VOC are 47 Hz and 53 Hz, which are consistent with the eigenvalue calculation results. The correctness of the conclusion that the DFIG based on VM-DPC is more stable than the DFIG based on VOC under weak grids is verified.

[0075] In some embodiments, the control strategy comparative analysis system of the doubly-fed wind turbine may include multiple functional modules composed of computer program segments. The computer programs of each program segment in the control strategy comparative analysis system of the doubly-fed wind turbine can be stored in the memory of the computer device and executed by at least one processor to execute (see details in Figure 1 description) the functions of the control strategy comparative analysis of the doubly-fed wind turbine.

[0076] In this embodiment, the control strategy comparative analysis system of the doubly-fed wind turbine can be divided into multiple functional modules according to the functions it performs, such as Figure 9As shown. The functional modules of the system may include: a system construction module, an RSC unified power transfer function calculation module, a GSC unified power transfer function calculation module, and a comparison and analysis module. The modules referred to in the present invention refer to a series of computer program segments that can be executed by at least one processor and can complete fixed functions, and are stored in a memory. In this embodiment, the functions of each module will be described in detail in subsequent embodiments. The system includes: The system construction module respectively constructs a doubly-fed wind turbine system adopting VM-DPC based on an induction generator, an RSC, and a GSC, and obtains first electrical parameters and first operating state variables; constructs a doubly-fed wind turbine system adopting VOC, and obtains second electrical parameters and second operating state variables; The RSC unified power transfer function calculation module obtains the power control transfer function of the RSC adopting VM-DPC based on the first electrical parameters and the first operating state variables; obtains the power control transfer function of the RSC adopting VOC based on the second electrical parameters and the second operating state variables; constructs the unified power transfer function on the RSC side based on the power control transfer function of the RSC adopting VM-DPC and the power control transfer function of the RSC adopting VOC; The GSC unified power transfer function calculation module obtains the power control transfer function of the GSC adopting VM-DPC based on the first electrical parameters and the first operating state variables; obtains the power control transfer function of the GSC adopting VOC based on the second electrical parameters and the second operating state variables; when not considering the voltage control outer loop, constructs the unified power transfer function on the GSC side based on the power control transfer function of the GSC adopting VM-DPC and the power control transfer function of the GSC adopting VOC; The comparison and analysis module defines the control parameters of VM-DPC and VOC based on the unified power transfer function on the RSC side and the unified power transfer function on the GSC side, respectively obtains the complex vector comprehensive impedance of the doubly-fed wind turbine based on VM-DPC and the doubly-fed wind turbine based on VOC in combination with the control parameters, and conducts a comparative analysis on the complex vector comprehensive impedance.

[0077] By respectively constructing each module of the doubly-fed wind turbine system based on VM-DPC and VOC, obtaining relevant electrical parameters and operating state variables, then calculating the unified power transfer functions on the RSC and GSC sides, and then defining the control parameters based on these transfer functions, obtaining and comparing the complex vector comprehensive impedance of the doubly-fed wind turbine based on VM-DPC and VOC, it helps to comprehensively and deeply compare the control characteristics of VM-DPC and VOC in the doubly-fed wind turbine system, and provides a theoretical basis for system optimization.

[0078] Figure 10A schematic structural diagram of a terminal provided by an embodiment of the present invention. The terminal can be used to execute the method for comparative analysis of the control strategy of a doubly-fed wind turbine provided by the embodiment of the present invention.

[0079] Among them, the terminal may include: a processor, a memory, and a communication unit. These components communicate through one or more buses. Those skilled in the art can understand that the structure of the server shown in the figure does not constitute a limitation to the present invention. It can be a bus structure, a star structure, and may also include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0080] Among them, the memory can be used to store the execution instructions of the processor. The memory can be implemented by any type of volatile or non-volatile storage terminal 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 read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk, or optical disc. When the execution instructions in the memory are executed by the processor, the terminal can execute some or all of the steps in the above method embodiments.

[0081] The processor is the control center of the storage terminal, connecting various parts of the entire electronic terminal through various interfaces and lines. By running or executing the software programs and / or modules stored in the memory, and by calling the data stored in the memory, it executes various functions of the electronic terminal and / or processes data. The processor can be composed of an integrated circuit (IC). For example, it can be composed of a single packaged IC, or can be composed of multiple packaged ICs with the same or different functions connected together. For example, the processor may only include a central processing unit (CPU). In the embodiment of the present invention, the CPU can be a single operation core or can include multiple operation cores.

[0082] The communication unit is used to establish a communication channel so that the storage terminal can communicate with other terminals. Receive user data sent by other terminals or send user data to other terminals.

[0083] The present invention also provides a computer-readable storage medium. Among them, the computer storage medium can store a program, and when the program is executed, it can include some or all of the steps in the embodiments provided by the present invention. The storage medium can be a magnetic disk, an optical disc, a read-only memory (ROM), a random access memory (RAM), etc.

[0084] Therefore, for the technical effects achievable by this embodiment, reference can be made to the descriptions above, and details will not be elaborated herein.

[0085] Those skilled in the art can clearly understand that the technologies in the embodiments of the present invention can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solutions in the embodiments of the present invention, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc, etc., which can store program codes, and includes several instructions for causing a computer terminal (which can be a personal computer, a server, or a second terminal, a network terminal, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0086] For the same or similar parts among the various embodiments in this specification, reference can be made to each other. In particular, for the terminal embodiments, since they are basically similar to the method embodiments, the descriptions are relatively simple, and for the relevant parts, reference can be made to the descriptions in the method embodiments.

[0087] In the several embodiments provided by the present invention, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are only illustrative. For example, the division of the modules is only a logical function division. In actual implementation, there can be other division methods. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of systems or modules can be in electrical, mechanical, or other forms.

[0088] The modules described as separate components may or may not be physically separated. The components displayed as modules may or may not be physical modules, that is, they can be located in one place, or can be distributed to multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0089] In addition, in each embodiment of the present invention, the various functional modules can be integrated into one processing module, or each module can exist physically alone, or two or more modules can be integrated into one module.

[0090] Although the present invention has been described in detail by reference to the accompanying drawings and in conjunction with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions should all be within the scope of the present invention. / Any person skilled in the art within the technical scope disclosed by the present invention can easily conceive of changes or substitutions, and they should all be covered within the protection scope of the present invention.

Claims

1. A comparative analysis method for the control strategy of a doubly-fed wind turbine, characterized in that, It includes the following steps: Based on the induction generator, RSC, and GSC, respectively, construct a doubly-fed wind turbine system using VM-DPC and obtain the first electrical parameters and the first operating state variables; construct a doubly-fed wind turbine system using VOC and obtain the second electrical parameters and the second operating state variables; Obtain the power control transfer function of the RSC using VM-DPC based on the first electrical parameters and the first operating state variables; obtain the power control transfer function of the RSC using VOC based on the second electrical parameters and the second operating state variables; construct a unified power transfer function on the RSC side based on the power control transfer function of the RSC using VM-DPC and the power control transfer function of the RSC using VOC; Obtain the power control transfer function of the GSC using VM-DPC based on the first electrical parameters and the first operating state variables; obtain the power control transfer function of the GSC using VOC based on the second electrical parameters and the second operating state variables; when not considering the voltage control outer loop, construct a unified power transfer function on the GSC side based on the power control transfer function of the GSC using VM-DPC and the power control transfer function of the GSC using VOC; Define the control parameters of VM-DPC and VOC based on the unified power transfer function on the RSC side and the unified power transfer function on the GSC side, and respectively obtain the complex vector comprehensive impedance of the doubly-fed wind turbine based on VM-DPC and the doubly-fed wind turbine based on VOC, and conduct a comparative analysis on the complex vector comprehensive impedance.

2. The comparative analysis method for the control strategy of the doubly-fed wind turbine according to claim 1, characterized in that, The specific process of obtaining the power control transfer function of the RSC using VM-DPC based on the first electrical parameters and the first operating state variables includes: Obtain the stator power, stator voltage equation, and rotor voltage equation based on the first electrical parameters and the first operating state variables. The stator voltage equation includes the stator resistance and stator flux linkage, and the rotor voltage equation includes the rotor resistance and rotor flux linkage; Obtain the stator flux linkage calculation equation and rotor flux linkage calculation equation based on the first electrical parameters and the first operating state variables. The stator flux linkage calculation equation includes the stator inductance, stator current, and rotor current, and the rotor flux linkage calculation equation includes the rotor inductance, stator current, and rotor current to calculate the rotor flux linkage; Substitute the calculated stator flux linkage calculation equation, rotor flux linkage calculation equation, stator voltage equation, and rotor voltage equation into the stator power to obtain the control equation of the RSC's VM-DPC; Obtain the active power control and reactive power control voltage modulation variables of the RSC's VM-DPC based on the control equation of the RSC's VM-DPC, establish a linear relationship between the voltage modulation variable and the stator power, and obtain the reference value of the voltage modulation variable based on the linear relationship and the preset stator power reference value; Conduct a Laplace transform on the control equation of the RSC's VM-DPC and substitute the reference value of the voltage modulation variable to obtain the power control transfer function of the RSC using VM-DPC.

3. The comparative analysis method for the control strategy of the doubly-fed fan according to claim 2, wherein The specific process of obtaining the power control transfer function of the RSC using VOC based on the second electrical parameters and the second operating state variables includes: Transform the stator flux linkage calculation equation, rotor flux linkage calculation equation, stator voltage equation, and rotor voltage equation to dq the coordinate system, and obtain the relationship between the rotor voltage and rotor current, and the relationship between the stator power and rotor current; Obtain the rotor current reference value of VOC on the RSC side based on the stator power reference value on the RSC side and the characteristics of the coordinate system; Combine the relationship between the rotor voltage and the rotor current, the relationship between the stator power and the rotor current, and the stator power reference value of VOC on the RSC side to obtain the power control transfer function of the RSC using VOC.

4. The comparative analysis method for the control strategy of a doubly-fed wind turbine according to claim 3, characterized in that The power control transfer function of the RSC using VM-DPC is specifically: The power control transfer function of the RSC using VOC is specifically: Among them, is the stator active power, is the reference value of the stator active power, is the stator reactive power, is the reference value of the stator reactive power, is the actual value of the rotor current on the q axis, is the reference value of the rotor current on the q axis, and are the PI parameters of VM-DPC on the RSC side, is the Laplace operator, is the stator resistance, is the rotor inductance, is the excitation inductance, and are the PI parameters of VOC on the RSC side, is the rotor resistance, is the stator inductance; Since the stator resistance in the doubly-fed wind turbine is approximately equal to the rotor resistance and the stator inductance is approximately equal to the rotor inductance, the unified power transfer function on the RSC side constructed based on the power control transfer function of the RSC using VM-DPC and the power control transfer function of the RSC using VOC is specifically: Among them, =( R s + R r ) / 2, =( L s + L r ) / 2.

5. The comparative analysis method for the control strategy of a doubly-fed wind turbine according to claim 1, characterized in that Obtaining the power control transfer function of the GSC using VM-DPC based on the first electrical parameter and the first operating state variable specifically includes: Obtain the relationships among the output power of the GSC, the GSC voltage, the GSC current, and the stator voltage based on the first electrical parameter and the first operating state variable; Combine the output power of the GSC and the relationships among the GSC voltage, the GSC current, and the stator voltage to obtain the control equation of VM-DPC of the GSC; Based on the control equation of VM-DPC of the GSC, obtain the nonlinear active control and reactive control voltage modulation variables, establish a linear relationship between the voltage modulation variable and the output power of the GSC, and obtain the reference value of the voltage modulation variable based on the linear relationship and the preset output power reference value of the GSC; Perform Laplace transform on the control equation of VM-DPC of the GSC and substitute the reference value of the voltage modulation variable to obtain the power control transfer function of the GSC using VM-DPC.

6. The comparative analysis method for the control strategy of a doubly-fed wind turbine according to claim 5, characterized in that Obtain the power control transfer function of the GSC using VOC based on the second electrical parameter and the second operating state variable. The ultimate goals of VM-DPC and VOC are both to achieve the control of active power and reactive power. When not considering the voltage outer loop, VM-DPC realizes power control by determining the linear relationship between the voltage modulation variable and the GSC power, and VOC indirectly realizes power control by converting the GSC power reference value into a current reference value and through the current inner loop control. The two are approximately equivalent in the power control transfer path. Therefore, the unified power transfer function on the GSC side constructed based on the power control transfer function of the GSC using VM-DPC and the power control transfer function of the GSC using VOC is specifically: Among them, is the active power output of the GSC, is the reference value of the GSC active power, is the reactive power output of the GSC, is the reference value of the GSC reactive power, and are the PI parameters of the VM-DPC or VOC current loop on the GSC side, is the resistance of the GSC filter, is the inductance of the GSC filter, is the Laplace operator.

7. The comparative analysis method for the control strategy of the doubly-fed wind turbine according to claim 1, characterized in that The comparative analysis of the complex vector comprehensive impedance specifically includes: performing amplitude-frequency and phase-frequency characteristic comparison, main diagonal element comparison, and non-main diagonal element comparison on the two complex vector comprehensive impedances respectively.

8. A control strategy comparison and analysis system for a doubly-fed wind turbine, characterized in that When the system is implemented, execute the comparative analysis method of the control strategy of the doubly-fed wind turbine described in any one of claims 1-7. The system includes: A system construction module that respectively constructs a doubly-fed wind turbine system using VM-DPC based on an induction generator, an RSC, and a GSC and obtains the first electrical parameter and the first operating state variable, and constructs a doubly-fed wind turbine system using VOC and obtains the second electrical parameter and the second operating state variable; The RSC unified power transfer function calculation module obtains the power control transfer function of the RSC using VM-DPC based on the first electrical parameter and the first operating state variable; obtains the power control transfer function of the RSC using VOC based on the second electrical parameter and the second operating state variable; constructs the unified power transfer function on the RSC side based on the power control transfer function of the RSC using VM-DPC and the power control transfer function of the RSC using VOC; The GSC unified power transfer function calculation module obtains the power control transfer function of the GSC using VM-DPC based on the first electrical parameter and the first operating state variable; obtains the power control transfer function of the GSC using VOC based on the second electrical parameter and the second operating state variable; when not considering the voltage control outer loop, constructs the unified power transfer function on the GSC side based on the power control transfer function of the GSC using VM-DPC and the power control transfer function of the GSC using VOC; The comparison and analysis module defines the control parameters of VM-DPC and VOC based on the unified power transfer function on the RSC side and the unified power transfer function on the GSC side, obtains the complex vector comprehensive impedance of the doubly-fed wind turbine based on VM-DPC and the doubly-fed wind turbine based on VOC respectively in combination with the control parameters, and conducts a comparative analysis on the complex vector comprehensive impedance.

9. A terminal, characterized in that, Comprising: A memory for storing the control strategy comparison and analysis program of the doubly-fed wind turbine; A processor for implementing the steps of the control strategy comparison and analysis method of the doubly-fed wind turbine as described in any one of claims 1-7 when executing the control strategy comparison and analysis program of the doubly-fed wind turbine.

10. A computer-readable storage medium, characterized in that, The control strategy comparison and analysis program of the doubly-fed wind turbine is stored on the readable storage medium, and when the control strategy comparison and analysis program of the doubly-fed wind turbine is executed by the processor, the steps of the control strategy comparison and analysis method of the doubly-fed wind turbine as described in any one of claims 1-7 are implemented.

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