Double-fed synchronous wind power generation mechanism and control method thereof

Abstract

The invention relates to the technical field of wind power generation devices, and provides a double-fed synchronous wind power generation mechanism and a control method thereof. The wind power generation mechanism comprises a wind wheel, a step-up gear box, a stator-free adjustable-speed motor, an electro-magnetic synchronous generator, a converter, an inverter, a main switch and a transformer. The stator-free adjustable-speed motor comprises an outer rotor and an inner rotor. The wind wheel is connected with the step-up gear box; the step-up gear box is connected with the outer rotor; the converter is connected with the inner rotor; the converter is connected with the transformer; the electro-magnetic synchronous generator is connected with the inner rotor; the electro-magnetic synchronous generator is connected with the inverter; the electro-magnetic synchronous generator is connected with one end of the main switch; the inverter is connected with the transformer; the other end of the main switch is connected with a power grid; the transformer is connected with a power grid. By using the doubly-fed synchronous wind power generation system, the problems that an existing speed regulation type wind turbine generator is difficult in component machining and difficult in technology popularization are solved.

Description

Technical Field

[0001] The invention relates to the technical field of wind power generation devices and provides a double-fed synchronous wind power generation mechanism and a control method thereof. Background Art

[0002] Building a new power system with new energy as the main body is the direction of my country's energy transformation. However, a high-proportion new energy power system faces frequency and voltage stability problems, which are the key to the reliability of the power system and the quality of power for users. The new energy power system represented by wind energy, due to its intermittent and volatile nature, leads to a decrease in the inertia of the power system, affecting frequency stability. First, wind power equipment lacks the mechanical inertia of synchronous generators, resulting in slow frequency response and increased frequency fluctuations. Secondly, although the power electronic equipment in the wind power system has improved the conversion efficiency, it cannot provide inertia, further weakening the frequency stability. At the same time, wind turbines are insufficient in reactive power. Due to the capacity limitation of the converter, it is difficult for wind turbines to provide sufficient support when the voltage fluctuates or the reactive demand is large, resulting in voltage instability. When the system fault is restored, the insufficient reactive power output of the wind turbine may cause voltage collapse and affect the voltage stability of the system. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention provides a double-fed synchronous wind power generation mechanism and a control method thereof, which achieves the technical effect of improving the frequency stability of the power system and improving the voltage stability of the power system.

[0004] The present invention provides a double-fed synchronous wind power generation mechanism, comprising: a wind wheel, a speed increasing gear box, a statorless speed regulating motor, an electrically excited synchronous generator, a converter, an inverter, a main switch and a transformer. The statorless speed regulating motor comprises an outer rotor and an inner rotor; The wind wheel is connected to the input end of the speed increasing gear box; The output end of the speed increasing gearbox is connected to the outer rotor; One end of the converter is connected to the inner rotor; The other end of the converter is connected to the first input end of the transformer; The first end of the electrically excited synchronous generator is connected to the inner rotor; The second end of the electrically excited synchronous generator is connected to the input end of the inverter; The third terminal of the electrically excited synchronous generator is connected to one terminal of the main switch; The output end of the inverter is connected to the second input end of the transformer; The other end of the main switch is connected to the power grid; The transformer output end is connected to the power grid.

[0005] According to a doubly-fed synchronous wind power generation mechanism provided by the present invention, the converter is a back-to-back dual PWM (Pulse Width Modulation) converter.

[0006] According to a doubly-fed synchronous wind power generation mechanism provided by the present invention, the wind wheel is mechanically connected to the speed-increasing gearbox through a low-speed shaft, the speed-increasing gearbox is mechanically connected to the outer rotor through a high-speed shaft, and the inner rotor is mechanically connected to the rotor of the electrically excited synchronous generator through a synchronous shaft.

[0007] According to a doubly-fed synchronous wind power generation mechanism provided by the present invention, the doubly-fed synchronous wind power generation mechanism has three operating states: a subsynchronous operating state, a supersynchronous operating state and a synchronous operating state: Subsynchronous operation state: the outer rotor speed of the statorless speed regulating motor is lower than the inner rotor speed; Super synchronous operation state: the outer rotor speed of the statorless speed regulating motor is higher than the inner rotor speed; Synchronous operation state: The outer rotor speed of the statorless speed-regulating motor is equal to the inner rotor speed.

[0008] According to a doubly-fed synchronous wind power generation mechanism provided by the present invention, in a subsynchronous operation state, the statorless speed regulating motor absorbs electric energy from the power grid through a converter, and generates electricity through a synchronous shaft-assisted electrically excited synchronous generator.

[0009] According to a doubly-fed synchronous wind power generation mechanism provided by the present invention, in the super-synchronous operation state, the statorless speed regulating motor sends electric energy to the power grid through the converter to assist the electrically excited synchronous generator in generating electricity.

[0010] The present invention also provides a control method for a doubly-fed synchronous wind power generation mechanism, comprising: S1: measuring the speed of the inner rotor and the speed of the outer rotor, and calculating a speed reference value; obtaining a torque command through a PI regulator according to the speed of the inner rotor, the speed of the outer rotor and the speed reference value; S2: establishing a voltage equation of the statorless speed regulating motor in a two-phase rotating coordinate system according to the torque command, and obtaining a motor adjustment model according to the voltage equation; S3: Obtain a command signal through space vector pulse width modulation according to the motor adjustment model, and adjust the rotation speed of the inner rotor and the rotation speed of the outer rotor according to the command signal.

[0011] According to a control method for a doubly-fed synchronous wind power generation mechanism provided by the present invention, step S1 comprises: S11: measuring the rotation speed of the inner rotor and the rotation speed of the outer rotor, and calculating the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding: in, is the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding, is the electrical angular velocity of the outer rotor, is the electrical angular velocity of the inner rotor; S12: Calculate the speed reference value : When the electrically excited synchronous generator does not meet the grid connection conditions, the formula is: in, is the synchronous speed of the electrically excited synchronous generator; When the electrically excited synchronous generator has reached the grid-connected condition, the formula is: in, is the optimal value of the speed of the outer rotor; S13: Perform PI adjustment on the electric angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding and the speed reference value to obtain a torque command .

[0012] According to a control method for a doubly-fed synchronous wind power generation mechanism provided by the present invention, step S2 comprises: S21: Establishing the voltage equation of the statorless speed regulating motor in a two-phase rotating coordinate system: in, For the inner rotor The voltage component below the axis, is the resistance of the inner rotor, For the inner rotor The current component below the axis, For the inner rotor The inductance below the axis, For the inner rotor The current component below the axis, For the inner rotor The inductance below the axis, for About Time The first derivative of For the inner rotor The voltage component below the axis, for About Time The first derivative of is the maximum value of the flux linkage between the magnetic field of the outer rotor and each phase winding of the inner rotor; In steady state, we have: .

[0013] S22: Calculate the current reference value according to the torque command: in, is the number of pole pairs of the statorless speed regulating motor; S23: Perform PI adjustment according to the voltage equation and the torque command to obtain a motor adjustment model: in, for Axis feedforward compensation term, for Axis feedforward compensation term, is the proportionality coefficient of the current loop, is the integral coefficient of the current loop.

[0014] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: The present invention provides a doubly-fed synchronous wind power generation mechanism and a control method thereof. By forming a doubly-fed synchronous wind power generation system from mature motor components such as a permanent magnet outer rotor, a wound inner rotor, and an electrically excited synchronous generator, the problem of difficult processing of components and difficult technology promotion of existing speed-regulating wind turbines can be solved. Secondly, in this system, only the statorless speed-regulating motor needs a converter that matches its power, while the synchronous generator does not need a converter, that is, it belongs to a partial power converter unit, which can solve the problem of large converter power of existing speed-regulating wind turbines. Finally, the decoupling control strategy of the statorless speed-regulating motor operating at a variable speed and constant frequency within the full wind speed range can solve the problem of low power generation efficiency of existing speed-regulating wind turbines.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a structural schematic diagram of a double-fed synchronous wind power generation mechanism provided by the present invention.

[0018] Figure 2 It is a flow chart of a control method of a doubly-fed synchronous wind power generation mechanism provided by the present invention.

[0019] Figure 3 It is a structural block diagram of a control method for a double-fed synchronous wind power generation mechanism provided by the present invention.

[0020] Reference numerals: 1. Wind wheel; 2. Speed ​​increasing gearbox; 3. Statorless speed regulating motor; 4. Electrically excited synchronous generator; 5. Back-to-back dual PWM converter; 6. Inverter; 7. Main switch; 8. Transformer; 9. Outer rotor; 10. Inner rotor. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0022] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0023] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0024] Combine the following Figures 1 to 3 The present invention is described.

[0025] Example like Figure 1 As shown, Figure 1 The structure diagram of a doubly-fed synchronous wind power generation mechanism provided by the present invention includes: a wind wheel 1, a speed increasing gearbox 2, a statorless speed regulating motor 3, an electrically excited synchronous generator 4, a converter, an inverter 6, a main switch 7 and a transformer 8. The statorless speed regulating motor 3 comprises an outer rotor 9 and an inner rotor 10; The wind wheel 1 is connected to the input end of the speed increasing gearbox 2; The output end of the speed increasing gearbox 2 is connected to the outer rotor 9; One end of the converter is connected to the inner rotor 10; The other end of the converter is connected to the first input end of the transformer 8; The first end of the electrically excited synchronous generator 4 is connected to the inner rotor 10; The second end of the electrically excited synchronous generator 4 is connected to the input end of the inverter 6; The third end of the electrically excited synchronous generator 4 is connected to one end of the main switch 7; The output end of the inverter 6 is connected to the second input end of the transformer 8; The other end of the main switch 7 is connected to the power grid; The output end of the transformer 8 is connected to the power grid.

[0026] Specifically, the converter is a back-to-back dual PWM converter 5 .

[0027] The wind wheel 1 is mechanically connected to the speed-increasing gearbox 2 through a low-speed shaft, and the wind energy absorbed by the wind wheel 1 is converted into mechanical energy and then transmitted to the speed-increasing gearbox 2. After the first-stage speed increase of the speed-increasing gearbox 2, the high-speed shaft of the speed-increasing gearbox 2 is mechanically connected to the outer rotor 9 of the statorless speed-regulating motor, and the mechanical energy is transmitted to the statorless speed-regulating motor 3. The inner rotor 10 of the statorless speed-regulating motor is mechanically connected to the rotor of the EESG (Electrically Excited Synchronous Generator) through a synchronous shaft, and part of the mechanical energy is transmitted to the EESG. The wound inner rotor of the statorless speed-regulating motor is electrically connected to the grid through a back-to-back dual PWM converter 5. According to the different operating states of the statorless speed-regulating motor under different wind speeds, the statorless speed-regulating motor 3 absorbs electric energy from the grid or sends electric energy to the grid through the converter, thereby realizing a two-way electric energy exchange between the statorless speed-regulating motor 3 and the grid.

[0028] The rotor of the EESG is mechanically connected to the inner rotor 10 of the statorless speed regulating motor through a synchronous shaft, and is electrically connected to an excitation device to adjust the reactive power of the system. The stator of the EESG is connected to the power grid through a main switch. Before the EESG reaches the grid connection conditions, the main switch is in an off state. The system only exchanges energy with the power grid through the statorless speed regulating motor. The control target of the statorless speed regulating motor is that the speed of the inner rotor reaches the synchronous speed of the EESG so that the EESG can be directly connected to the grid without a converter. When the EESG meets the grid connection conditions, the main switch is closed, and the EESG converts the mechanical energy transmitted by the statorless speed regulating motor through the synchronous shaft into electrical energy and transmits it to the power grid. Since the EESG is directly connected to the power grid without a converter, the present invention has the characteristics of a "synchronous unit". At the same time, the present invention realizes a two-way energy exchange with the power grid through a converter connected to the wound inner rotor of the statorless speed regulating motor and the stator side of the EESG, and the system has the characteristics of a "doubly fed unit". After EESG is connected to the grid, the control target of the statorless speed-regulating motor is to track the optimal speed corresponding to the maximum power point of the wind turbine under different wind speeds so as to capture the maximum wind energy.

[0029] Specifically, the wind wheel 1 is mechanically connected to the speed-increasing gearbox 2 via a low-speed shaft, the speed-increasing gearbox 2 is mechanically connected to the outer rotor 9 via a high-speed shaft, and the inner rotor 10 is mechanically connected to the rotor of the electrically excited synchronous generator 4 via a synchronous shaft.

[0030] The speed of the outer rotor of the statorless speed regulating motor is , the inner rotor speed is , the frequency on the inner rotor winding is The rotating magnetic field formed by the alternating current has a speed of According to the principle of electromechanics that energy exchange can only be carried out when the magnetic fields of the inner and outer rotors are relatively stationary, the speed relationship of the statorless speed regulating motor can be obtained: when hour, If the value is positive, the rotating magnetic field formed by the excitation current of the inner rotor winding has the same speed direction as the inner and outer rotor speeds; otherwise, If the value is negative, the rotating magnetic field speed is opposite to the speed of the inner and outer rotors.

[0031] Substituting the relationship between speed and frequency into the speed relationship of the statorless speed regulating motor, the excitation current frequency of the inner rotor winding can be obtained: In the formula, The number of pole pairs of the statorless speed regulating motor. Change the frequency of the excitation current of the inner rotor winding Adjustable .

[0032] The positive direction of the statorless speed regulating motor is defined by the convention of the generator. The speed is positive when it rotates counterclockwise, the torque is positive when it rotates clockwise, the mechanical power is positive when it is input into the statorless speed regulating motor, and the electromagnetic power is positive when it is output from the statorless speed regulating motor.

[0033] The torque on the outer rotor of the statorless speed regulating motor is the mechanical torque. and the electromagnetic torque exerted by the inner rotor on the outer rotor The torque on the rotor of the statorless speed regulating motor is the mechanical torque. and the electromagnetic torque exerted by the outer rotor on the inner rotor , thus, the motion equation of the statorless speed regulating motor can be obtained: in, is the moment of inertia of the outer rotor, is the moment of inertia of the inner rotor, is the mechanical angular velocity of the outer rotor, is the mechanical angular velocity of the inner rotor, when the number of pole pairs of the statorless speed regulating motor is When , there is the following relationship: , , is the electrical angular velocity of the outer rotor, is the electrical angular velocity of the inner rotor, To find the time derivative.

[0034] When the outer rotor speed is stable, , when the inner rotor speed is stable, there is Since the electromagnetic torques on the inner and outer rotors are equal in value and opposite in direction, that is, , so when the speed of the statorless speed regulating motor is stable, the torque relationship is: When the speed of the statorless speed-regulating motor is stabilized, the mechanical torques of its inner and outer rotors are equal and reverse.

[0035] When the positive direction of a statorless speed regulating motor is specified according to the generator convention, the power relationship is: In the formula, is the electric power output by the statorless speed regulating motor, is the mechanical power of the outer rotor of the statorless speed regulating motor, It is the mechanical power of the rotor inside the input statorless speed regulating motor.

[0036] The relationship between the speed, torque and power of a statorless speed regulating motor is: Since the positive direction of the statorless speed regulating motor is specified by the generator convention, in the actual power flow, the mechanical power of the outer rotor of the statorless speed regulating motor is Always flows into the statorless speed regulating motor, the mechanical power of the rotor inside the statorless speed regulating motor Always outflow statorless speed regulating motor.

[0037] Specifically, the doubly-fed synchronous wind power generation mechanism has three operating states: a subsynchronous operating state, a supersynchronous operating state and a synchronous operating state.

[0038] Subsynchronous operation state: The outer rotor speed of the statorless speed regulating motor is lower than the inner rotor speed, that is, , When the magnetic field speed is 0.05, it is in subsynchronous operation state. Opposite to the specified positive direction, , which is clockwise. Same as the specified positive direction, , is clockwise; Opposite to the specified positive direction, , is counterclockwise; the two are equal in magnitude and in opposite directions, . Same as the specified positive direction, , indicating that there is mechanical power input to the statorless speed regulating motor; Opposite to the specified positive direction, , indicating that mechanical power is output from the statorless speed regulating motor; Opposite to the specified positive direction, , indicating that electromagnetic power is input into the statorless speed regulating motor. Therefore, the statorless speed regulating motor absorbs electric energy from the power grid through the converter, converts the electric energy into mechanical energy through the synchronous shaft, and assists the electrically excited synchronous generator in generating electricity.

[0039] Super synchronous operation state: the outer rotor speed of the statorless speed regulating motor is higher than the inner rotor speed, that is, , , in super synchronous operation state. Same as the specified positive direction, , which is counterclockwise. Same as the specified positive direction, , is clockwise; Opposite to the specified positive direction, , is counterclockwise; the two are equal in magnitude and in opposite directions, . Same as the specified positive direction, , indicating that there is mechanical power input to the statorless speed regulating motor; Opposite to the specified positive direction, , indicating that mechanical power is output from the statorless speed regulating motor; Same as the specified positive direction, , indicating that electromagnetic power is output from the statorless speed regulating motor. The statorless speed regulating motor sends electric energy to the power grid through the converter to assist the electrically excited synchronous generator in generating electricity.

[0040] Synchronous operation state: The outer rotor speed of the statorless speed regulating motor is equal to the inner rotor speed, that is, , . Same as the specified positive direction, , is clockwise; Opposite to the specified positive direction, , is counterclockwise; the two are equal in magnitude and in opposite directions, . Same as the specified positive direction, , indicating that there is mechanical power input to the statorless speed regulating motor; Opposite to the specified positive direction, , indicating that mechanical power is output from the statorless speed regulating motor; , indicating that there is no active power exchange between the statorless speed regulating motor and the power grid.

[0041] Specifically, Figure 2 As shown, the present invention also provides a control method for a doubly-fed synchronous wind power generation mechanism, comprising: S1: measuring the speed of the inner rotor and the speed of the outer rotor, and calculating a speed reference value; obtaining a torque command through a PI regulator according to the speed of the inner rotor, the speed of the outer rotor and the speed reference value; S2: establishing a voltage equation of the statorless speed regulating motor in a two-phase rotating coordinate system according to the torque command, and obtaining a motor adjustment model according to the voltage equation; S3: Obtain a command signal through space vector pulse width modulation according to the motor adjustment model, and adjust the rotation speed of the inner rotor and the rotation speed of the outer rotor according to the command signal.

[0042] Specifically, step S1 includes: S11: measuring the rotation speed of the inner rotor and the rotation speed of the outer rotor, and calculating the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding: in, is the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding, is the electrical angular velocity of the outer rotor, is the electrical angular velocity of the inner rotor; S12: Calculate the speed reference value : When the electrically excited synchronous generator does not meet the grid connection conditions, the formula is: in, is the synchronous speed of the electrically excited synchronous generator; When the electrically excited synchronous generator has reached the grid-connected condition, the formula is: in, is the optimal value of the speed of the outer rotor; S13: Perform PI adjustment on the electric angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding and the speed reference value to obtain a torque command .

[0043] Specifically, step S2 includes: S21: Establishing the voltage equation of the statorless speed regulating motor in a two-phase rotating coordinate system: in, For the inner rotor The voltage component below the axis, is the resistance of the inner rotor, For the inner rotor The current component below the axis, For the inner rotor The inductance below the axis, For the inner rotor The current component below the axis, For the inner rotor The inductance below the axis, for About Time The first derivative of For the inner rotor The voltage component below the axis, for About Time The first derivative of is the maximum value of the flux linkage between the magnetic field of the outer rotor and each phase winding of the inner rotor; In steady state, we have: ; S22: Calculate the current reference value according to the torque command: in, is the number of pole pairs of statorless speed regulating motor; S23: Perform PI adjustment according to the voltage equation and the torque command to obtain a motor adjustment model: in, is the proportionality coefficient of the current loop, is the integral coefficient of the current loop.

[0044] like Figure 3 As shown, Figure 3 The structure diagram of a double-fed synchronous wind power generation mechanism control method provided by the present invention is shown in FIG. , outer rotor speed , after subtraction with the reference value The speed deviation is obtained by the PI regulator. Shaft current reference value , The shaft current reference value is 0, that is, , respectively, with the actual value The current deviation is obtained after the PI regulator. and , after superimposing the cross-coupling voltage, we get and ,Will The shaft voltage value passes Transform, get Shaft component voltage and Shaft component voltage , the driving signal of the inner rotor side converter is obtained through space vector control (SVPWM, Space Vector Pulse Width Modulation).

[0045] The current of the inner rotor side converter passes through Transformation and Feedback to steps S1 and S2 for re-adjustment. After the statorless speed regulating motor is controlled by space vector control, the inner rotor position angle of the statorless speed regulating motor is measured. , the outer rotor position angle of the statorless speed regulating motor , calculate the difference between the inner rotor position and the outer rotor position , by measuring the electrical angular velocity of the outer rotor , the electrical angular velocity of the inner rotor , calculate the difference between the outer rotor electrical angular velocity and the inner rotor electrical angular velocity ,Will and Feedback is sent to steps S1 and S2 for readjustment.

[0046] The present invention is dedicated to solving the problems of difficult component processing, difficult technology promotion, large converter power, low power generation efficiency, etc. in existing speed-regulating wind turbines. First, the doubly-fed synchronous wind power generation system designed by the present invention is composed of mature motor components such as permanent magnet outer rotor, wound inner rotor, and electrically excited synchronous generator, which can solve the problems of difficult component processing and difficult technology promotion in existing speed-regulating wind turbines. Secondly, in this system, only the statorless speed-regulating motor needs a converter that matches its power, while the synchronous generator does not need a converter, that is, it belongs to a partial power converter unit, which can solve the problem of large converter power in existing speed-regulating wind turbines. Finally, the decoupling control strategy of the statorless speed-regulating motor with variable speed and constant frequency operation in the full wind speed range can solve the problem of low power generation efficiency in existing speed-regulating wind turbines.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0048] It should be noted that the embodiments of the present disclosure may be implemented by hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic: the software portion may be stored in a memory and executed by an appropriate instruction execution system such as a microprocessor or dedicated design hardware. Those skilled in the art will appreciate that the above-described apparatus and methods may be implemented using computer executable instructions and / or contained in a processor control code, such as a programmable memory or a data carrier such as an optical or electronic signal carrier providing such code.

[0049] In addition, although the operation of the method of the present disclosure is described in a particular order in the accompanying drawings, this does not require or imply that these operations must be performed in this particular order, or that all the operations shown must be performed to achieve the desired result. On the contrary, the steps depicted in the flow chart can change the order of execution. Additionally or alternatively, some steps can be omitted, multiple steps can be combined into one step for execution, and / or one step can be decomposed into multiple steps for execution. It should also be noted that the features and functions of two or more devices according to the present disclosure can be embodied in one device. Conversely, the features and functions of a device described above can be further divided into being embodied by multiple devices.

[0050] Although the present disclosure has been described with reference to several specific embodiments, it should be understood that the present disclosure is not limited to the specific embodiments disclosed. The present disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A doubly-fed synchronous wind power generation mechanism, characterized in that: include: Wind wheel, speed increasing gearbox, statorless speed regulating motor, electrically excited synchronous generator, converter, inverter and transformer: The statorless speed regulating motor comprises an outer rotor and an inner rotor; The wind wheel is connected to the input end of the speed increasing gear box; The output end of the speed increasing gearbox is connected to the outer rotor; One end of the converter is connected to the inner rotor; The other end of the converter is connected to the first input end of the transformer; The first end of the electrically excited synchronous generator is connected to the inner rotor; The second end of the electrically excited synchronous generator is connected to the input end of the inverter; The output end of the inverter is connected to the second input end of the transformer.

2. A doubly-fed synchronous wind power generation mechanism according to claim 1, characterized in that: The converter is a back-to-back dual PWM transformer.

3. A doubly-fed synchronous wind power generation mechanism according to claim 1, characterized in that: The wind wheel is mechanically connected to the speed-increasing gearbox via a low-speed shaft, the speed-increasing gearbox is mechanically connected to the outer rotor via a high-speed shaft, and the inner rotor is mechanically connected to the rotor of the electrically excited synchronous generator via a synchronous shaft.

4. A doubly-fed synchronous wind power generation mechanism according to claim 1, characterized in that: The doubly-fed synchronous wind power generation mechanism has three operating states: subsynchronous operating state, supersynchronous operating state and synchronous operating state: Subsynchronous operation state: the outer rotor speed of the statorless speed regulating motor is lower than the inner rotor speed; Super synchronous operation state: the outer rotor speed of the statorless speed regulating motor is higher than the inner rotor speed; Synchronous operation state: The outer rotor speed of the statorless speed-regulating motor is equal to the inner rotor speed.

5. A doubly-fed synchronous wind power generation mechanism according to claim 4, characterized in that: In the subsynchronous operation state, the statorless speed regulating motor absorbs electric energy from the power grid through the converter, and generates electricity through the synchronous shaft to assist the electrically excited synchronous generator.

6. A doubly-fed synchronous wind power generation mechanism according to claim 4, characterized in that: In the super-synchronous operation state, the statorless speed regulating motor sends electric energy to the power grid through the converter to assist the electrically excited synchronous generator in generating electricity.

7. A control method for a doubly-fed synchronous wind power generation mechanism, used to control a doubly-fed synchronous wind power generation mechanism as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S1: measuring the speed of the inner rotor and the speed of the outer rotor, and calculating a speed reference value; obtaining a torque command through a PI regulator according to the speed of the inner rotor, the speed of the outer rotor and the speed reference value; S2: establishing a voltage equation of the statorless speed regulating motor in a two-phase rotating coordinate system according to the torque command, and obtaining a motor adjustment model according to the voltage equation; S3: Obtain a command signal through space vector pulse width modulation according to the motor adjustment model, and adjust the rotation speed of the inner rotor and the rotation speed of the outer rotor according to the command signal.

8. A control method for a doubly-fed synchronous wind power generation mechanism according to claim 7, characterized in that: Step S1 includes: S11: measuring the rotation speed of the inner rotor and the rotation speed of the outer rotor, and calculating the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding: in, is the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding, is the electrical angular velocity of the outer rotor, is the electrical angular velocity of the inner rotor; S12: Calculate the speed reference value : When the electrically excited synchronous generator does not meet the grid connection conditions, the formula is: in, is the synchronous speed of the electrically excited synchronous generator; When the electrically excited synchronous generator has reached the grid-connected condition, the formula is: in, is the optimal value of the speed of the outer rotor; S13: Perform PI adjustment on the electric angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding and the speed reference value to obtain a torque command .

9. A control method for a doubly-fed synchronous wind power generation mechanism according to claim 8, characterized in that: Step S2 includes: S21: Establish the statorless speed regulating motor in a two-phase rotating coordinate system The voltage equation is: in, For the inner rotor The voltage component below the axis, is the resistance of the inner rotor, For the inner rotor The current component below the axis, For the inner rotor The inductance below the axis, For the inner rotor The current component below the axis, For the inner rotor The inductance below the axis, for About Time The first derivative of For the inner rotor The voltage component below the axis, for About Time The first derivative of is the maximum value of the magnetic flux linkage between the magnetic field of the outer rotor and each phase winding of the inner rotor; In steady state, we have: ； S22: Calculate the current reference value according to the torque command: in, For inner rotor Shaft current reference value, For inner rotor Shaft current reference value, is the number of pole pairs of the statorless speed regulating motor; S23: Perform PI adjustment according to the voltage equation and the torque command to obtain a motor adjustment model: in, for Axis feedforward compensation term, for Axis feedforward compensation term, is the proportionality coefficient of the current loop, is the integral coefficient of the current loop.

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