Control strategy comparison and analysis method, system, terminal and medium for doubly-fed wind turbine

Abstract

The application relates to the technical field of wind power, and particularly provides a control strategy comparison and analysis method, system, terminal and medium for a double-fed wind turbine, which comprises the following steps: constructing a double-fed wind turbine system adopting VM-DPC and obtaining first electrical parameters and first operating state variables, constructing a double-fed wind turbine system adopting VOC and obtaining second electrical parameters and second operating state variables; constructing a unified power transfer function on the RSC side based on a power control transfer function of an RSC adopting VM-DPC and a power control transfer function of an RSC adopting VOC; constructing a unified power transfer function on the GSC side based on a power control transfer function of a GSC adopting VM-DPC and a power control transfer function of a GSC adopting VOC; obtaining complex vector comprehensive impedances of the double-fed wind turbine based on VM-DPC and VOC respectively, and comparing and analyzing the complex vector comprehensive impedances. The accuracy of the analysis and comparison results is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wind power, and particularly relates to a control strategy comparison and analysis method, system, terminal and medium for a doubly-fed wind turbine. BACKGROUND

[0002] The doubly-fed wind turbine is a common wind power generation device, and the impedance characteristics of the doubly-fed wind turbine can be effectively evaluated to assess the wind power grid stability. Since the dynamic characteristics of the doubly-fed wind turbine are mainly dominated by the control strategy thereof, different control strategies will significantly affect the 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, the voltage-modulated direct power control (VM-DPC) proposed for voltage source converters has attracted extensive attention. The control does not require a phase-locked loop, and has the advantage of small steady-state harmonics due to the use of a fixed switching frequency pulse width modulation. An existing patent extends the VM-DPC for the control of the doubly-fed wind turbine, and verifies the superior steady-state and transient performance of the VM-DPC by comparing the VM-DPC with the typical voltage-oriented vector control. αβ However, in the comparison between the VM-DPC and the voltage-oriented vector control in the existing patent, the parameters of the two controls are randomly selected. In fact, the structures of the two controls are different, and the principles of parameter selection are also different. Therefore, direct comparison of the two controls cannot guarantee that their dynamic characteristics have a unified benchmark, and the accuracy of the analysis and comparison results is difficult to guarantee.

[0004] SUMMARY

[0005] In view of the above problems in the prior art, the application provides a control strategy comparison and analysis method, system, terminal and medium for a doubly-fed wind turbine to solve the above technical problems.

[0006] In a first aspect, the application provides a control strategy comparison and analysis method for a doubly-fed wind turbine, comprising:

[0007] constructing a doubly-fed wind turbine system adopting VM-DPC based on an induction generator, an RSC and a GSC, and obtaining first electrical parameters and first operating state variables, constructing a doubly-fed wind turbine system adopting VOC, and obtaining second electrical parameters and second operating state variables;

[0008] obtaining a power control transfer function of the RSC adopting the VM-DPC based on the first electrical parameters and the first operating state variables, obtaining a power control transfer function of the RSC adopting the VOC based on the second electrical parameters and the second operating state variables, and constructing a unified power transfer function on the 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; ​

[0009] obtaining a power control transfer function of the GSC using VM-DPC based on the first electrical parameter and the first operating state variable; obtaining a power control transfer function of the GSC using VOC based on the second electrical parameter and the second operating state variable; constructing 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 when not considering the voltage control outer loop;

[0010] defining 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, obtaining complex vector comprehensive impedances of the double-fed fan based on VM-DPC and the double-fed fan based on VOC respectively in combination with the control parameters, and comparing and analyzing the complex vector comprehensive impedances.

[0011] In an optional implementation, the obtaining of the power control transfer function of the RSC using VM-DPC based on the first electrical parameter and the first operating state variable specifically comprises:

[0012] obtaining a stator power, a stator voltage equation and a rotor voltage equation based on the first electrical parameter and the first operating state variable, the stator voltage equation comprising a stator resistance and a stator flux linkage, and the rotor voltage equation comprising a rotor resistance and a rotor flux linkage;

[0013] obtaining a stator flux linkage calculation equation and a rotor flux linkage calculation equation based on the first electrical parameter and the first operating state variable, the stator flux linkage calculation equation comprising a stator inductance, a stator current and a rotor current, and the rotor flux linkage calculation equation comprising a rotor inductance, a stator current and a rotor current to calculate a rotor flux linkage;

[0014] substituting the obtained stator flux linkage calculation equation, rotor flux linkage calculation equation, stator voltage equation and rotor voltage equation into the stator power to obtain a control equation of the VM-DPC of the RSC;

[0015] obtaining active control and reactive control voltage modulation variables of the VM-DPC on the RSC side based on the control equation of the VM-DPC of the RSC, establishing a linear relationship between the voltage modulation variables and the stator power, and obtaining a reference value of the voltage modulation variables based on the linear relationship and a preset stator power reference value;

[0016] performing Laplace transform on the control equation of the VM-DPC of the RSC and substituting the reference value of the voltage modulation variables to obtain the power control transfer function of the RSC using VM-DPC.

[0017] In an optional implementation, the obtaining of the power control transfer function of the RSC using VOC based on the second electrical parameter and the second operating state variable specifically comprises:

[0018] The stator flux linkage calculation equation, the rotor flux linkage calculation equation, and the stator voltage equation and the rotor voltage equation are transformed into the d-q coordinate system, and the relationship between the rotor voltage and the rotor current and the relationship between the stator power and the rotor current are obtained. dq

[0019] The rotor current reference value of the RSC side VOC is obtained based on the stator power reference value of the RSC side and the characteristics of the coordinate system.

[0020] The power control transfer function of the RSC using the VOC is obtained by combining 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 the RSC side VOC.

[0021] In an optional embodiment, the power control transfer function of the RSC using the VM-PC is specifically:

[0022]

[0023] The power control transfer function of the RSC using the VOC is specifically:

[0024]

[0025] 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 d-axis, q is the reference value of the rotor current on the d-axis, is the actual value of the rotor current on the q-axis, q is the reference value of the rotor current on the q-axis, and are PI parameters of the RSC side VM-DPC, is the Laplace operator, is the stator resistance, is the rotor inductance, is the field inductance, and are PI parameters of the RSC side VOC, is the rotor resistance, is the stator inductance.

[0026] Since the stator resistance is approximately equal to the rotor resistance and the stator inductance is approximately equal to the rotor inductance in the doubly-fed wind turbine, the unified power transfer function of the RSC side is specifically constructed based on the power control transfer function of the RSC using the VM-DPC and the power control transfer function of the RSC using the VOC:

[0027] ​

[0028] wherein, R s R r s L r L

[0029] In an optional embodiment, obtaining the power control transfer function of the GSC employing the VM-DPC based on the first electrical parameter and the first operating state variable specifically comprises:

[0030] obtaining the relationship between the GSC output power, the GSC voltage and the GSC current and the stator voltage based on the first electrical parameter and the first operating state variable;

[0031] combining the GSC output power and the relationship between the GSC voltage and the GSC current and the stator voltage to obtain the control equation of the VM-DPC of the GSC;

[0032] obtaining the nonlinear active control and reactive control voltage modulation variable based on the control equation of the VM-DPC of the GSC, establishing the linear relationship between the voltage modulation variable and the GSC output power, and obtaining the reference value of the voltage modulation variable based on the linear relationship and the preset GSC output power reference value;

[0033] performing Laplace transform on the control equation of the VM-DPC of the GSC and substituting the reference value of the voltage modulation variable to obtain the power control transfer function of the GSC employing the VM-DPC.

[0034] In an optional embodiment, obtaining the power control transfer function of the GSC employing the VOC based on the second electrical parameter and the second operating state variable, the ultimate purpose of the VM-DPC and the VOC is to realize the control of the active power and the reactive power, without considering the voltage outer loop, the VM-DPC realizes the power control by determining the linear relationship between the voltage modulation variable and the GSC power, the VOC realizes the power control indirectly by converting the GSC power reference value into the current reference value and through the current inner loop control, both of which are approximately equivalent in the power control transfer path, therefore, constructing the unified power transfer function of the GSC side based on the power control transfer function of the GSC employing the VM-DPC and the power control transfer function of the GSC employing the VOC specifically comprises:

[0035]

[0036] wherein, is the GSC output active power, ​​​​​​is a reference value of the active power of the GSC, is the output reactive power of the GSC, is a reference value of the reactive power of the GSC, and is a PI parameter 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.

[0037] In an optional implementation, the comparative analysis of the complex vector comprehensive impedances specifically includes: comparative analysis of the amplitude-frequency and phase-frequency characteristics, the main diagonal element, and the non-main diagonal element of the two complex vector comprehensive impedances, respectively.

[0038] In a second aspect, the present application provides a control strategy comparative analysis system for a doubly-fed wind turbine, which implements the control strategy comparative analysis method for the doubly-fed wind turbine as described above, and comprises:

[0039] a system construction module, which constructs a doubly-fed wind turbine system adopting VM-DPC based on the induction generator, the RSC, and the GSC, and obtains first electrical parameters and first operating state variables, and constructs a doubly-fed wind turbine system adopting VOC and obtains second electrical parameters and second operating state variables;

[0040] an RSC unified power transfer function calculation module, which 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, and 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;

[0041] a GSC unified power transfer function calculation module, which 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, and 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 when not considering the voltage control outer loop;

[0042] a comparative analysis module, which 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 complex vector comprehensive impedance of the doubly-fed wind turbine based on VOC in combination with the control parameters, and performs comparative analysis of the complex vector comprehensive impedances.

[0043] In a third aspect, a terminal is provided, comprising:

[0044] a processor, a memory, wherein,

[0045] the memory is configured to store a computer program,

[0046] the processor is configured to call and run the computer program from the memory, so that the terminal executes the method of the terminal described above.

[0047] In a fourth aspect, a computer readable storage medium is provided, the computer readable storage medium has instructions stored therein, when the instructions are run on a computer, the computer executes the method described in the above aspects.

[0048] The beneficial effects of the present application are that the control strategy comparison and analysis method, system, terminal and medium of the doubly-fed wind turbine provided by the present application respectively construct the doubly-fed wind turbine system of VM-DPC and VOC, obtain relevant parameters and variables, and then obtain the power control transfer function of RSC and GSC under two control modes, construct a unified power transfer function, define control parameters and obtain complex vector comprehensive impedance for comparison and analysis, which helps to deeply understand the electrical characteristics and performance differences of the doubly-fed wind turbine under two control strategies, provides a theoretical basis and analysis method for optimizing the control of the doubly-fed wind turbine system and improving the stability and operation efficiency of the system, and improves the accuracy of the analysis and comparison results.

[0049] In addition, the design principle of the present application is reliable, the structure is simple, and it has very wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the present application, the drawings needed to be used in the description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0051] Figure 1 is a schematic flow chart of the control strategy comparison and analysis method of the doubly-fed wind turbine according to an embodiment of the present application.

[0052] Figure 2 is a DFIG structure diagram based on VM-DPC according to an embodiment of the present application.

[0053] Figure 3 is a VOC structure diagram of DFIG according to an embodiment of the present application.

[0054] Figure 4is a comparison result of DFIG impedance based on VM-DPC and VOC in an embodiment of the present application.

[0055] Fig. 5(a) is a characteristic value trajectory when SCR is reduced from 3 to 1.9 under VM-DPC in an embodiment of the present application.

[0056] Fig. 5(b) is a characteristic value trajectory when SCR is reduced from 3 to 1.9 under VOC in an embodiment of the present application.

[0057] Figure 6 is a comparison result of power step response of DFIGs based on VM-DPC and VOC in an embodiment of the present application; (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.

[0058] Figure 7 is a simulation result of DFIG based on VM-DPC in an embodiment of the present application.

[0059] Fig. 8(a) is a waveform diagram of a simulation result of DFIG based on VOC in an embodiment of the present application.

[0060] Fig. 8(b) is an FFT of a simulation result of DFIG based on VOC in an embodiment of the present application.

[0061] Figure 9 is a schematic block diagram of a control strategy comparison and analysis system of a double-fed wind turbine in an embodiment of the present application.

[0062] Figure 10 is a structural schematic diagram of a terminal provided in an embodiment of the present application. DETAILED DESCRIPTION

[0063] In order to make the person skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing specific embodiments only and is not intended to be limiting of the application.

[0065] The control strategy comparison and analysis method of the doubly-fed wind turbine provided by the embodiments of the present application is executed by a computer device, and accordingly, the control strategy comparison and analysis system of the doubly-fed wind turbine runs in the computer device.

[0066] Figure 1 is a schematic flow chart of the control strategy comparison and analysis method of the doubly-fed wind turbine according to an embodiment of the present application. In the flow chart, Figure 1 The execution subject can be a control strategy comparison and analysis system of a doubly-fed wind turbine. According to different requirements, the order of the steps in the flow chart can be changed, and some steps can be omitted.

[0067] As Figure 1 shown, the method comprises:

[0068] S1, based on the induction generator, the RSC and the GSC, a doubly-fed wind turbine system using VM-DPC is constructed, and first electrical parameters and first operating state variables are obtained, and a doubly-fed wind turbine system using VOC is constructed, and second electrical parameters and second operating state variables are obtained;

[0069] A hardware platform containing the induction generator, the RSC and the GSC is built. When the doubly-fed system using VM-DPC is constructed, the stator power, the rotor voltage and current and other information are detected by sensors, the RSC is controlled according to the algorithm, and the GSC DC bus voltage is maintained. When the doubly-fed system using VOC is constructed, the RSC and GSC current components are controlled after the voltage and current coordinates are transformed, and parameters and variables are obtained by sensors, so as to obtain the electrical parameters and operating state variables of the two systems respectively.

[0070] The acquisition of the first electrical parameters and the first operating state variables and 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 detailed basis for comparing and analyzing the performance differences of the two control strategies.

[0071] 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 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;

[0072] Based on the obtained parameters and variables of the VM-DPC system, the RSC power control transfer function is derived from the power deviation and voltage vector relationship; for the VOC system, the RSC transfer function is derived from the current and power relationship combined with the control strategy, and then the unified power transfer function on the RSC side is constructed through analysis and processing.

[0073] The mathematical model of RSC power control under two control strategies is accurately established, and the dynamic relationship between input (such as power reference value, etc.) and output (such as actual power, etc.) is clearly expressed in the form of transfer function.

[0074] S3, 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 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;

[0075] According to the parameters and variables of the VM-DPC system, the working principle and control target of the GSC are analyzed, and the power control transfer function is derived through circuit equations and power equations, and the unified power transfer function on the GSC side is constructed by simplifying and refining when not considering the voltage outer loop.

[0076] 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.

[0077] 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, and 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 respectively by combining the control parameters, and compare and analyze the complex vector comprehensive impedance.

[0078] According to the control parameters defined by the unified power transfer function on the RSC and GSC sides, the complex vector comprehensive impedance under two control strategies is obtained by substituting into the doubly-fed wind turbine model using complex vector analysis method, and then the amplitude, phase, frequency characteristics, etc. are compared and analyzed.

[0079] Obtaining and comparing complex vector impedance provides an important basis for evaluating the system's stability, harmonic characteristics, and interaction characteristics with the power grid.

[0080] Optionally, as an embodiment of the present invention, the detailed topology of a doubly-fed induction generator (DFIG) based on voltage-modulated direct power control (VM-DPC) is as follows: Figure 2 As shown. Among them u s and u r These are the stator and rotor voltages, respectively. i s and i r These are the stator and rotor currents, respectively. u g and i g These represent GSC voltage and current, respectively. i t It is the total current at the DFIG point of common coupling (PCC). u dc This is the DC bus voltage. Unless otherwise specified, bold variables represent... αβ Complex vectors in a coordinate system, for example, u s = u sα +j u sβ By applying VM-DPC, the rotor-side converter (RSC) is responsible for regulating the stator power, while the grid-side converter (GSC) controls the DC voltage.

[0081] Optionally, as an embodiment of the present invention, the voltage-oriented vector control (VOC) structure of the DFIG is as follows: Figure 3 As shown. The RSC uses current PI modulation to achieve open-loop control of the stator power. The GSC uses a dual-loop control structure with an outer voltage loop and an inner current loop, where... k PQ =2 / 3 U sd This is for voltage-controlled gain.

[0082] Optionally, as one embodiment of the present application, the step S2 of obtaining the power control transfer function of the RSC using the VM-DPC based on the first electrical parameter and the first operating state variable specifically comprises:

[0083] The VM-DPC is based on the pre-defined voltage modulation variable to directly decouple the converter output power in the stator αβ coordinate system, and then generates the converter voltage instruction value. For RSC control, since the control object is the stator power, it is necessary to derive the dynamic relationship between the stator power and the RSC output rotor voltage to construct the control equation of the VM-DPC of the RSC.

[0084] The stator active P s and reactive Q s In the αβ coordinate system, it can be written as:

[0085] (1)

[0086] In order to eliminate the stator current in the stator power, the stator and rotor voltage equations of the DFIG main circuit are established in the αβ coordinate system, and are expressed as follows:

[0087] (2)

[0088] wherein ω m is the rotor speed, R s and R r are the stator and rotor resistances, respectively. The stator flux ψ s and the rotor flux ψ r can be calculated by the stator and rotor currents, as follows:

[0089] (3)

[0090] wherein L s and L r are the stator and rotor inductances, respectively, L m is the excitation inductance.

[0091] Therefore, by taking the differential of the stator power (1) and substituting (2) and (3), the control equation of the VM-DPC of the RSC can be finally obtained:

[0092] (4)

[0093] where σ αβ =1- L s L r / L m L m is the leakage inductance coefficient of the VM-DPC, ω s denotes the grid fundamental angular frequency. The rotor voltage and current angular frequencies ω r and ω m are related by ω r = ω s - ω m .

[0094] The terms u rP and u rQ in the above equations are defined as the active and reactive control voltage modulation variables of the RSC-side VM-DPC, respectively, which are nonlinearly related to the stator and rotor voltages. By defining the voltage modulation variables, an approximately linear relationship between them and the stator output power can be established, which is expressed as:

[0095] (5)

[0096] where k s =-2 σ αβ L m is the VM-DPC gain of the RSC. In a large capacity DFIG system, R r is usually relatively small and has little impact on the control performance. Therefore, the compensation term C rP representing the coupling between the stator voltage and rotor current C rQ can be neglected.

[0097] Thus, for a given stator power reference value, the decoupling term k s ω r Q s and k s ωr P s Then, the active and reactive power are controlled by PI modulation to generate u rP and u rQ Finally, according to the definition of the voltage modulation variable in (4), the voltage modulation transformation equation (6) is deduced to calculate the rotor voltage command value in the αβ coordinate system. The implementation of the control principle of the RSC-side VM-DPC is shown in the left blue box in Figure 2 .

[0098] (6)

[0099] Therefore, the reference value of the voltage modulation variable of the RSC-side VM-DPC can be expressed in the frequency domain as: Figure 2

[0100] (7)

[0101] wherein k p,rsc and k i,rsc are the PI parameters of the RSC-side VM-DPC.

[0102] The Laplace transform is performed on (4), and (7) is substituted into (4) to replace u rP and u rQ , so that the power control transfer function of the RSC using the VM-DPC is obtained:

[0103] (8).

[0104] Alternatively, as an embodiment of the present application, in step 2, the power control transfer function of the RSC using the VOC is obtained based on the second electrical parameter and the second operating state variable, and specifically includes:

[0105] The VOC of the RSC is synchronized with the grid voltage based on the PLL, and the current control is performed in the dq coordinate system. Therefore, the stator and rotor voltage equations and the flux linkage equations of the DFIG main circuit need to be transformed to the dq coordinate system, and the relationship between the rotor voltage and the rotor current is deduced as:

[0106] (9)

[0107] wherein σ =1- L m L ​m / L s L r is the leakage inductance coefficient of VOC. dq In a coordinate system, variables can be defined in ways other than having the subscript "dq". αβ All variables are consistent in the coordinate system, for example, u sdq = u sd +j u sq Therefore, the design resulting from this Figure 3 The RSC current control shown has the following expression:

[0108] (10)

[0109] in k p,ir and k i,ir The PI parameter for VOC on the RSC side.

[0110] Furthermore, in dq In a coordinate system, the stator power and rotor current have the following relationship:

[0111] (11)

[0112] Based on the above relationships, the rotor current can be calculated using a given stator power reference value. d shaft and q Axis component reference values.

[0113] Therefore, substituting (10) into (9) and combining it with (11), we can establish the power control transfer function of RSC using VOC:

[0114] (12)

[0115] It should be noted that, according to (11), the stator active power and rotor current d The active power control transfer function can be directly established because it is proportional to the shaft components. However, the stator reactive power, although proportional to the rotor current... q The axial components have a linear relationship, but due to the existence of component 3... u sd u sd / 2 ω s L s This makes it impossible to directly derive the reactive power control transfer function. Therefore, (12) only gives the rotor current. qThe control transfer function of the axis component, which can approximately reflect the dynamic characteristics of the RSC reactive power control.

[0116] Optionally, as an embodiment of the present application, the step S2 of constructing the unified power transfer function of the RSC side is specifically:

[0117] It can be found from the observation (8) and (12) that the power transfer functions of the two controls have the same form, and the difference is only in the coefficient of the first order term in the denominator. s However, the resistance or inductance of the stator and rotor in the DFIG is extremely close, R s L r and R r L s The numerical values are not much different. Therefore, the average value of the resistance and the average value of the inductance of the stator and rotor can be used to define the unified power transfer function of the VM-DPC and VOC of the RSC side:

[0118] (13)

[0119] Wherein =( R s + R r ) / 2, =( L s + L r ) / 2. According to the unified power transfer function of the VM-DPC and VOC of the RSC side, only the PI parameters need to be consistent to ensure that the two controls have the same stator power control dynamic characteristics under ideal grid conditions.

[0120] Optionally, as an embodiment of the present application, the step S3 specifically includes:

[0121] For the GSC control, the outer ring of the GSC control using the VM-DPC adopts PI modulation to maintain the DC bus voltage constant, and the inner ring of the control adopts the VM-DPC to control the inverter output power according to the GSC power reference value generated by the DC voltage outer ring. Therefore, the control equation of the VM-DPC of the GSC is the dynamic relationship between the GSC output power and the GSC voltage.

[0122] αβ The GSC output active power P g and reactive power Q g in the coordinate system can be expressed as:

[0123] (14)

[0124] Meanwhile, the relationship between the GSC voltage and the GSC current and the stator voltage can be obtained according to the GSC filter circuit as follows:

[0125] (15)

[0126] wherein, R g and L g are the resistance and inductance of the GSC filter.

[0127] Referring to the derivation process of the RSC side control equation, the differential of (14) is taken and substituted into (15) to eliminate the GSC current, and the control equation of the GSC VM-DPC can be obtained as follows:

[0128] (16)

[0129] Similarly, the nonlinear active control and reactive control voltage modulation variables of the GSC side VM-DPC in (16) are u gP and u gQ respectively. The linear relationship between the GSC output power and the voltage modulation variables is as follows:

[0130] (17)

[0131] wherein k g = 2 L g / 3 is the VM-DPC gain of the GSC.

[0132] Therefore, for the GSC output power reference value given by the DC voltage control outer ring, the active and reactive control can also be achieved by PI modulation. Then, by setting the decoupling term k g ω s Q g and k g ω s P g the reference values of u gP and u gQ are generated. Finally, the reference values of αβGSC voltage command value in the coordinate system. The VM-DPC structure corresponding to the above GSC control principle is as shown in the right blue frame in FIG. 7. Figure 2

[0133] (18)

[0134] The converter using VM-DPC or VOC without voltage control outer loop has the same power control transfer function. Therefore, the unified power transfer function of GSC side VM-DPC and VOC can be directly defined as:

[0135] (19)

[0136] Wherein k p,gsc and k i,gsc are the PI parameters of the GSC side VM-DPC or VOC current loop. Therefore, by using the same control parameters and voltage control outer loop, the dynamic characteristics of the two GSC controls can be unified.

[0137] The converter using VM-DPC or VOC without voltage control outer loop has the same power control transfer function, because the basic principles and circuit structures of the internal power control have commonalities. In the power control process, both of them construct control logic around the relationship between the converter output power and the related electrical quantities. For VM-DPC, the control logic is constructed around the relationship between the stator αβ power and the rotor voltage in the stator dq coordinate system, and the core is to derive the control equation according to the dynamic relationship between the stator power and the rotor voltage, and further determine the approximate linear relationship between the voltage modulation variable and the stator output power, so as to realize power control. Although VOC has some differences in control method, such as current PI modulation and synchronization with grid voltage based on PLL in dq coordinate system for GSC power control, the basic circuit and electrical quantity relationship of power control are similar to VM-DPC in essence when the voltage control outer loop is not considered. This similarity makes the power control transfer functions of the two consistent after removing the influencing factor of voltage control outer loop.

[0138] Optionally, as an embodiment of the present application, step S4 specifically comprises:

[0139] VM-DPC realizes power control in the αβ coordinate system, and the complex vector comprehensive impedance of DFIG based on VM-DPC considering mechanical and GSC dynamics is derived in the coordinate system as shown in FIG. 8. Figure 2 Z DPC Meanwhile, based onFigure 3 DFIG in VM-DPC αβ The complex vector impedance in the dq coordinate system can be established as Z VOC The grid impedance is not considered in the analysis of DFIG impedance characteristics, 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 uniform transfer function, so that the power tracking dynamic characteristics of the two controls are consistent. The wind speed V w 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. P t Q t

[0140] Table 1 DFIG parameters

[0141]

[0142] 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 shown in Figure 4 From the figure, it can be seen that the two impedances have similar amplitude-frequency and phase-frequency variation rules near 50 Hz, and both have strong nonlinearity. Then, further analysis is made 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 exhibit negative resistance characteristics is also narrower. This indicates that under the uniform power control dynamic characteristics, the DFIG based on VM-DPC is more stable than the DFIG based on VOC. As for the non-main diagonal elements of the DFIG impedance, below 100 Hz, the DFIG based on VOC has a larger amplitude, representing a more significant frequency coupling phenomenon. And above 100 Hz, the frequency coupling phenomenon of the DFIG based on VM-DPC is more significant.

[0143] Alternatively, as an embodiment of the present application, the stability of the DFIGs based on VM-DPC and VOC is compared under different grid strengths considering the grid impedance. The grid side uses an RL equivalent circuit, and its αβ The impedance in the dq coordinate system can be expressed as Z grid . The aggregate impedance Z agDPC = Z DPC + Z grid or Z ​​agVOC = Z VOC + Z grid The eigenvalues of the DFIG grid-connected system are equivalent to the determinant zeros of Z agDPC or Z agVOC Therefore, the small signal stability of the DFIG grid-connected system can be evaluated by checking whether all the determinant zeros of s agDPC or Z agVOC are located in the left half of the complex plane. αβ The first k The real parts of the determinant zeros are the same, and the imaginary parts are symmetric about ω s The pair of determinant zeros 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 frequency of the oscillation mode corresponding to the pair of determinant zeros in the αβ coordinate system, which reflects the frequency coupling.

[0144] The basic parameters of the DFIGs with VM-DPC or VOC are still referred to Table 1. The PI parameters of the two controls are guaranteed to be consistent, and the grid-connection stability of the DFIGs based on VM-DPC and VOC is compared under the condition of the same power control dynamic characteristics. Similarly, the wind speed is 12 m / s, and the active and reactive power outputs of the DFIG are 1.5 MW and 0 Mvar, respectively. The grid impedance is changed so that the short-circuit ratio (SCR) decreases from 3 to 1.9. The determinant zeros of the aggregated impedance of the DFIGs based on the two controls are calculated in turn. Then, the changes of the system eigenvalues with the grid short-circuit ratio are analyzed. 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 systems based on VM-DPC and VOC λ 1,2 ,λ 3,4 , λ The trajectory of 5 is shown in Figures 5(a) and 5(b), respectively. It can be seen from the figures that as the grid short-circuit ratio decreases, regardless of whether VM-DPC or VOC is used, the dominant eigenvalue gradually moves towards the imaginary axis. However, the eigenvalue corresponding to VOC... λ 1,2 It will first cross the imaginary axis and reach the right half of the plane, while the eigenvalues ​​corresponding to VM-DPC remain in the left half. s Plane. When the short-circuit ratio is 2.3, the corresponding VOC... λ 1 = 0.003 + j297.47 λ 2 = 0.003 + j330.85. This indicates that as the grid short-circuit ratio decreases, the grid strength weakens, and the stability of the VOC-based DFIG grid-connected system gradually weakens until it becomes unstable. In contrast, the VM-DPC-based DFIG can remain stable under the same grid strength. This demonstrates that, under the same power control dynamic characteristics, the VM-DPC-based DFIG has stronger resistance to small disturbances in weak grid conditions compared to the VOC-based DFIG. This is consistent with the conclusion of the comparison of DFIG impedances for the two controls in Section 2.

[0145] Optionally, as an embodiment of the present invention, the power point tracking characteristics of VM-DPC-based and VOC-based DFIGs will be analyzed by step analysis under ideal grid conditions with a given power reference value to verify the correctness of the unified transfer function. Simultaneously, simulations will be used to verify the stability comparison results of VM-DPC-based and VOC-based DFIGs under different grid intensities. These simulation verifications are all based on a DFIG simulation model built in MATLAB / Simulink. The basic parameters of the DFIG are shown in Table 1. The wind speed is 12 m / s, and the total active power and total reactive power output of the DFIG are 1.5 MW and 0 Mvar, respectively.

[0146] The power point tracking dynamics of VM-DPC-based and VOC-based DFIGs are compared using MATLAB / Simulink simulations. This example assumes ideal grid conditions, neglecting grid impedance and maintaining a constant grid voltage. The PI parameters for both control systems are kept consistent based on a unified power transfer function. Initially, both the total active and total reactive power of the DFIGs under both control systems are set to 0. At 10 seconds, the total active power reference value of the DFIGs under both control systems simultaneously steps to 1.5 MW. Simulation results under the two sets of RSC control parameters are shown below. Figure 6As shown in (a) and (b) of the figure, it can be seen from the figure that as long as the PI parameters of the two controls are consistent, the DFIGs under the two controls can have the same power point tracking characteristics under ideal grid conditions. This verifies the effectiveness of the proposed unified power transfer function.

[0147] The stability comparison results of the DFIG grid-connected systems corresponding to the two control methods described above were verified through simulation. The initial simulation state was set with a grid short-circuit ratio of 2.5, at which point the system maintained stable operation. During the simulation, the grid short-circuit ratio decreased to 2.4 at 11 seconds and further decreased to 2.3 at 15 seconds. The simulation results of the DFIG grid-connected systems based on VM-DPC and VOC are as follows: Figure 7 and Figure 8(a) , 8(b) As shown in the figure, when the grid short-circuit ratio decreases to 2.4, both control systems remain stable. However, when the grid short-circuit ratio continues to decrease to 2.3, the VM-DPC-based DFIG grid-connected system remains stable, while the VOC-based DFIG grid-connected system exhibits oscillations that gradually diverge. This is consistent with the changes in the dominant eigenvalues ​​of the system shown in Figure 5. Furthermore, the oscillation frequencies corresponding to VOC, calculated by FFT, are 47Hz and 53Hz, consistent with the eigenvalue calculation results. This verifies the correctness of the conclusion that the VM-DPC-based DFIG is more stable than the VOC-based DFIG under weak grid conditions.

[0148] In some embodiments, the control strategy comparison and analysis system for doubly-fed induction generators (DFIGs) may include multiple functional modules composed of computer program segments. The computer programs for each program segment in the DFIG control strategy comparison and analysis system may be stored in the memory of a computer device and executed by at least one processor to perform (see details). Figure 1 (Description) Function for comparative analysis of control strategies for doubly fed wind turbines.

[0149] In this embodiment, the control strategy comparison and analysis system for the doubly fed wind turbine can be divided into multiple functional modules based on its functions, such as... Figure 9 As shown. The system's functional modules may include: a system construction module, an RSC unified power transfer function calculation module, a GSC unified power transfer function calculation module, and a comparative analysis module. The module referred to in this invention is a series of computer program segments that can be executed by at least one processor and perform a fixed function, stored in memory. In this embodiment, the functions of each module will be detailed in subsequent embodiments. The system includes:

[0150] a system construction module, which constructs a DFIG system based on VM-DPC and obtains first electrical parameters and first operating state variables, and constructs a DFIG system based on VOC and obtains second electrical parameters and second operating state variables;

[0151] an RSC unified power transfer function calculation module, which obtains a power control transfer function of the RSC based on VM-DPC based on the first electrical parameters and the first operating state variables, obtains a power control transfer function of the RSC based on VOC based on the second electrical parameters and the second operating state variables, and constructs a unified power transfer function on the RSC side based on the power control transfer function of the RSC based on VM-DPC and the power control transfer function of the RSC based on VOC;

[0152] a GSC unified power transfer function calculation module, which obtains a power control transfer function of the GSC based on VM-DPC based on the first electrical parameters and the first operating state variables, obtains a power control transfer function of the GSC based on VOC based on the second electrical parameters and the second operating state variables, and constructs a unified power transfer function on the GSC side based on the power control transfer function of the GSC based on VM-DPC and the power control transfer function of the GSC based on VOC when not considering the voltage control outer loop;

[0153] a comparative analysis module, which defines 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 complex vector comprehensive impedances of the DFIG based on VM-DPC and the DFIG based on VOC respectively in combination with the control parameters, and performs comparative analysis on the complex vector comprehensive impedances.

[0154] By constructing the modules of the DFIG systems based on VM-DPC and VOC respectively, obtaining the related electrical parameters and operating state variables, and then calculating the unified power transfer functions on the RSC and GSC sides, and then defining the control parameters based on the transfer functions, obtaining and comparing the complex vector comprehensive impedances of the DFIGs based on VM-DPC and VOC, it is helpful to comprehensively and deeply compare the control characteristics of VM-DPC and VOC in the DFIG system and provide a theoretical basis for system optimization.

[0155] Figure 10 A terminal structure schematic diagram is provided for the embodiments of the present application, and the terminal can be used to execute the method for comparing and analyzing the control strategies of the DFIGs provided by the embodiments of the present application.

[0156] The terminal can 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 on the present application. It can be a bus structure or a star structure. It can also include more or fewer components than shown in the figure, or combine certain components, or arrange different components.

[0157] 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 storage, flash memory, magnetic disk or optical disk. When the execution instructions in the memory are executed by the processor, the terminal can execute part or all of the steps in the above method embodiments.

[0158] The processor is the control center of the storage terminal. It connects all parts of the electronic terminal through various interfaces and lines. It executes the software programs and / or modules stored in the memory and calls the data stored in the memory to perform various functions of the electronic terminal and / or process data. The processor can be composed of integrated circuits (ICs), such as a single packaged IC or multiple packaged ICs connected together. For example, the processor can only include a central processing unit (CPU). In the embodiments of the present application, the CPU can be a single operation core or can include multiple operation cores.

[0159] The communication unit is used to establish a communication channel so that the storage terminal can communicate with other terminals. It receives user data sent by other terminals or sends user data to other terminals.

[0160] The present application also provides a computer readable storage medium, wherein the computer storage medium can store a program which, when executed, can include part or all of the steps in each embodiment provided by the present application. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0161] Therefore, the technical effects achieved by the present embodiment can be referred to the description above, which will not be repeated here.

[0162] Those skilled in the art can clearly understand that the technical solutions in the embodiments of the present application can be implemented by means of software plus necessary universal hardware platforms. Based on such an understanding, the technical solutions in the embodiments of the present application can be embodied in the form of a software product, which is stored in a storage medium, such as a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and the like, and includes a plurality of instructions for causing a computer terminal (which can be a personal computer, a server, or a second terminal, a network terminal, or the like) to execute all or part of the steps of the methods described in the embodiments of the present application.

[0163] In the present specification, the same or similar parts among various embodiments can be referred to each other. In particular, for the terminal embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the description in the method embodiments.

[0164] In several embodiments provided by the present application, it should be understood that the disclosed system and method can be implemented in other ways. For example, the system embodiments described above are merely schematic. For example, the division of the modules is merely a logical function division. In actual implementation, another division manner can be used. For example, a plurality of modules or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the modules or components shown or discussed can be indirect coupling or communication connection through some interfaces. The coupling or communication connection can be electrical, mechanical or in other forms.

[0165] The modules illustrated as separate components can or can not be physically separate, and the components illustrated as modules can or can not be physical modules, i.e., can be located in one place or distributed on a plurality of network modules. Part or all of the modules can be selected according to actual needs to achieve the purpose of the embodiments.

[0166] In addition, each functional module in the various embodiments of the present application can be integrated into a processing module, or each module can exist physically independently, or two or more modules can be integrated into one module.

[0167] Although the present application has been described in detail with reference to the preferred embodiments, it should be understood that the application is not limited to those preferred embodiments. Various modifications and equivalents can be made by those skilled in the art without departing from the spirit and scope of the application. Any and all modifications and equivalents are intended to be included within the scope of the present application.

Claims

1. A method for comparing control strategies of doubly-fed wind generators, characterized in that, The method comprises the following steps: Based on the induction generator, RSC and GSC, a double-fed wind turbine system using VM-DPC is constructed, and first electrical parameters and first operating state variables are obtained, a double-fed wind turbine system using VOC is constructed, and second electrical parameters and second operating state variables are obtained; 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, and 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; Based on the first electrical parameters and the first operating state variables, a power control transfer function of the GSC using VM-DPC is obtained, based on the second electrical parameters and the second operating state variables, a power control transfer function of the GSC using VOC is obtained, and when the voltage control outer loop is not considered, 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 unified power transfer function on the GSC side is constructed; Based on the unified power transfer function on the RSC side and the unified power transfer function on the GSC side, control parameters of VM-DPC and VOC are defined, and based on the control parameters, a complex vector comprehensive impedance of the double-fed wind turbine based on VM-DPC and the double-fed wind turbine based on VOC is obtained, and the complex vector comprehensive impedances are compared and analyzed; The power control transfer function of the RSC using VM-DPC is specifically as follows: The power control transfer function of the RSC using VOC is specifically as follows: wherein, is the stator active power, is the stator active power reference, is the stator reactive power, is the stator reactive power reference, 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 the RSC side VM-DPC, is the Laplace operator, is the stator resistance, is the rotor inductance, is the field inductance, and are the PI parameters of the RSC side VOC, is the rotor resistance, is the stator inductance; Since the stator resistance is approximately equal to the rotor resistance and the stator inductance is approximately equal to the rotor inductance in the double-fed wind turbine, 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 as follows: wherein = (Rs+ Rr) / 2, = (Ls+ Lr) / 2.

2. The control strategy comparison analysis method of a doubly-fed wind turbine according to claim 1, characterized in that, Based on the first electrical parameters and the first operating state variables, the power control transfer function of the RSC using VM-DPC specifically comprises: Based on the first electrical parameters and the first operating state variables, a stator power, a stator voltage equation and a rotor voltage equation are obtained, the stator voltage equation comprises a stator resistance and a stator flux linkage, and the rotor voltage equation comprises a rotor resistance and a rotor flux linkage; Based on the first electrical parameters and the first operating state variables, a stator flux linkage calculation equation and a rotor flux linkage calculation equation are obtained, the stator flux linkage calculation equation comprises a stator inductance, a stator current and a rotor current, and the rotor flux linkage calculation equation comprises a rotor inductance, a stator current and a rotor current to calculate a rotor flux linkage; The calculated stator flux linkage calculation equation, rotor flux linkage calculation equation, stator voltage equation and rotor voltage equation are substituted into the stator power to obtain a control equation of the VM-DPC of the RSC; Based on the control equation of the VM-DPC of the RSC, active control and reactive control voltage modulation variables of the RSC side VM-DPC are obtained, a linear relationship between the voltage modulation variables and the stator power is established, and based on the linear relationship and a preset stator power reference value, a reference value of the voltage modulation variable is obtained. The Laplace transform is performed on the control equation of the VM-DPC of the RSC, and the reference value of the voltage modulation variable is substituted into the equation to obtain the power control transfer function of the RSC using the VM-DPC.

3. The control strategy comparison analysis method of a doubly-fed wind turbine according to claim 2, characterized in that, The power control transfer function of the RSC using the VOC is obtained based on the second electrical parameter and the second operating state variable, and the power control transfer functions of the VM-DPC and the VOC are finally used to realize the control of active power and reactive power. The stator flux linkage calculation equation, the rotor flux linkage calculation equation, the stator voltage equation and the rotor voltage equation are transformed into the dq coordinate system, and the relationship between the rotor voltage and the rotor current and the relationship between the stator power and the rotor current are obtained. The rotor current reference value of the RSC side VOC is obtained based on the stator power reference value of the RSC side and the characteristics of the coordinate system. The power control transfer function of the RSC using the VOC is obtained based on 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 the RSC side VOC.

4. The control strategy comparison analysis method of a doubly-fed wind turbine according to claim 1, characterized in that, The power control transfer function of the GSC using the VM-DPC is obtained based on the first electrical parameter and the first operating state variable, and the power control transfer functions of the VM-DPC and the VOC are finally used to realize the control of active power and reactive power. The GSC output power, the relationship between the GSC voltage and the GSC current and the stator voltage are obtained based on the first electrical parameter and the first operating state variable. The control equation of the VM-DPC of the GSC is obtained, and the linear relationship between the voltage modulation variable and the GSC output power is established. The power control transfer function of the GSC using the VM-DPC is obtained by performing the Laplace transform on the control equation of the VM-DPC of the GSC and substituting the reference value of the voltage modulation variable into the equation. The power control transfer function of the GSC using the VOC is obtained based on the second electrical parameter and the second operating state variable, and the power control transfer functions of the VM-DPC and the VOC are finally used to realize the control of active power and reactive power.

5. The control strategy comparison method of a doubly-fed wind turbine according to claim 4, wherein The power control transfer functions of the VM-DPC and the VOC are finally used to realize the control of active power and reactive power, and when the voltage outer loop is not considered, the VM-DPC realizes power control by determining the linear relationship between the voltage modulation variable and the GSC power, and the VOC indirectly realizes power control by converting the GSC power reference value into a current reference value and through the current inner loop, and the two are approximately equivalent in the power control transfer path, so the unified power transfer function of the GSC side is constructed based on the power control transfer function of the GSC using the VM-DPC and the power control transfer function of the GSC using the VOC. wherein, 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 is the PI parameter of the GSC side VM-DPC or VOC current loop, is the resistance of the GSC filter, is the inductance of the GSC filter, is the Laplace operator.

6. The control strategy comparison analysis method of a doubly-fed wind turbine according to claim 1, characterized in that, The complex vector comprehensive impedance is compared and analyzed, including the amplitude-frequency and phase-frequency characteristics comparison, the main diagonal element comparison and the non-main diagonal element comparison of the two kinds of complex vector comprehensive impedances.

7. A control strategy comparison system for doubly-fed wind generators, characterized by, The system implements the control strategy comparison and analysis method of the doubly-fed wind turbine according to any one of claims 1-6, and the system comprises: a system construction module, which constructs a DFIG system adopting VM-DPC based on the induction generator, the RSC and the GSC, and obtains first electrical parameters and first operating state variables, and constructs a DFIG system adopting VOC and obtains second electrical parameters and second operating state variables; an RSC unified power transfer function calculation module, which obtains a power control transfer function of the RSC adopting VM-DPC based on the first electrical parameters and the first operating state variables, obtains a power control transfer function of the RSC adopting VOC based on the second electrical parameters and the second operating state variables, and constructs a 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; a GSC unified power transfer function calculation module, which obtains a power control transfer function of the GSC adopting VM-DPC based on the first electrical parameters and the first operating state variables, obtains a power control transfer function of the GSC adopting VOC based on the second electrical parameters and the second operating state variables, and constructs a 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 when not considering the voltage control outer loop; a comparative analysis module, which defines 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 complex vector comprehensive impedances of the DFIG based on VM-DPC and the DFIG based on VOC respectively in combination with the control parameters, and performs comparative analysis on the complex vector comprehensive impedances; the power control transfer function of the RSC adopting VM-DPC is specifically as follows: the power control transfer function of the RSC adopting VOC is specifically as follows: wherein, is the stator active power, is the stator active power reference, is the stator reactive power, is the stator reactive power reference, 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 the RSC side VM-DPC, is the Laplace operator, is the stator resistance, is the rotor inductance, is the field inductance, and are the PI parameters of the RSC side VOC, is the rotor resistance, is the stator inductance; since the stator resistance is approximately equal to the rotor resistance and the stator inductance is approximately equal to the rotor inductance in the DFIG, the unified power transfer function on the RSC side constructed based on the power control transfer function of the RSC adopting VM-DPC and the power control transfer function of the RSC adopting VOC is specifically as follows: wherein = (Rs+ Rr) / 2, = (Ls+ Lr) / 2.

8. A terminal, characterized by comprising: comprises: a memory, configured to store a control strategy comparative analysis program of the DFIG; a processor, configured to implement the steps of the control strategy comparative analysis method of the DFIG according to any one of claims 1-6 when executing the control strategy comparative analysis program of the DFIG.

9. A computer-readable storage medium, characterized in that, The readable storage medium has the control strategy comparative analysis program of the DFIG stored thereon, and the steps of the control strategy comparative analysis method of the DFIG according to any one of claims 1-6 are implemented when the control strategy comparative analysis program of the DFIG is executed by the processor.

Images