A doubly-fed synchronous wind power generation mechanism and its control method

Abstract

The present invention relates to the technical field of wind power generation devices, and provides a doubly-fed synchronous wind power generation mechanism and a control method thereof. The wind power generation mechanism includes: a wind turbine, a speed increasing gearbox, 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 includes an outer rotor and an inner rotor; the wind turbine is connected to the speed increasing gearbox; the speed increasing gearbox is connected to the outer rotor; the converter is connected to the inner rotor; the converter is connected to the transformer; the electrically excited synchronous generator is connected to the inner rotor; the electrically excited synchronous generator is connected to the inverter; the electrically excited synchronous generator is connected to one end of the main switch; the inverter is connected to the transformer; the other end of the main switch is connected to the power grid; the transformer is connected to the power grid. By using the doubly-fed synchronous wind power generation system, the present invention solves the problems of difficult processing of components and difficult technical promotion of existing speed regulating wind turbines.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation devices, and provides a doubly-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 China's energy transformation. However, a high-proportion new energy power system faces problems of frequency and voltage stability, which are the key to the reliability of the power system and the power quality of users. In a new energy power system represented by wind energy, due to its intermittency and volatility, the inertia of the power system decreases, affecting frequency stability. First, wind power equipment lacks the mechanical inertia of a synchronous generator, resulting in slow frequency response and increased frequency fluctuations. Second, although the power electronic devices in the wind power system improve the conversion efficiency, they cannot provide inertia, further weakening the frequency stability. At the same time, wind turbines have deficiencies 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 power demand is large, resulting in voltage instability. When the system recovers from a fault, the insufficient reactive power output of the wind turbine may cause voltage collapse, affecting 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. For this reason, the present invention provides a doubly-fed synchronous wind power generation mechanism and a control method thereof, achieving the technical effects of improving the frequency stability of the power system and improving the voltage stability of the power system.

[0004] The present invention provides a doubly-fed synchronous wind power generation mechanism, including: a wind turbine, a speed-increasing gearbox, a statorless speed-regulating motor, an electrically excited synchronous generator, a converter, an inverter, a main switch, and a transformer.

[0005] The statorless speed-regulating motor includes an outer rotor and an inner rotor.

[0006] The wind turbine is connected to the input end of the speed-increasing gearbox.

[0007] The output end of the speed-increasing gearbox is connected to the outer rotor.

[0008] One end of the converter is connected to the inner rotor.

[0009] The other end of the converter is connected to the first input end of the transformer.

[0010] The first end of the electrically excited synchronous generator is connected to the inner rotor.

[0011] The second end of the electrically excited synchronous generator is connected to the input end of the inverter.

[0012] The third terminal of the electrically excited synchronous generator is connected to one end of the main switch;

[0013] The output terminal of the inverter is connected to the second input terminal of the transformer;

[0014] The other end of the main switch is connected to the power grid;

[0015] The output terminal of the transformer is connected to the power grid.

[0016] According to a doubly-fed synchronous wind power generating mechanism provided by the present invention, the converter is a back-to-back dual-PWM (Pulse Width Modulation) converter.

[0017] According to a doubly-fed synchronous wind power generating mechanism provided by the present invention, the wind turbine is mechanically connected to the speed increaser through a low-speed shaft, the speed increaser 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.

[0018] According to a doubly-fed synchronous wind power generating mechanism provided by the present invention, the said doubly-fed synchronous wind power generating mechanism has three operating states: sub-synchronous operating state, super-synchronous operating state and synchronous operating state:

[0019] Sub-synchronous operating state: The rotational speed of the outer rotor of the statorless speed-regulating motor is lower than that of the inner rotor;

[0020] Super-synchronous operating state: The rotational speed of the outer rotor of the statorless speed-regulating motor is higher than that of the inner rotor;

[0021] Synchronous operating state: The rotational speed of the outer rotor of the statorless speed-regulating motor is equal to that of the inner rotor.

[0022] According to a doubly-fed synchronous wind power generating mechanism provided by the present invention, in the sub-synchronous operating state, the statorless speed-regulating motor absorbs electric energy from the power grid through the converter and assists the electrically excited synchronous generator to generate electricity through the synchronous shaft.

[0023] According to a doubly-fed synchronous wind power generating mechanism provided by the present invention, in the super-synchronous operating state, the statorless speed-regulating motor sends out electric energy to the power grid through the converter and assists the electrically excited synchronous generator to generate electricity.

[0024] The present invention also provides a control method for a doubly-fed synchronous wind power generating mechanism, including:

[0025] S1: Measure the rotational speed of the inner rotor and the rotational speed of the outer rotor, and calculate the rotational speed reference value; Obtain the torque command through a PI regulator according to the rotational speed of the inner rotor, the rotational speed of the outer rotor and the rotational speed reference value;

[0026] S2: Establish the voltage equation of the statorless speed-regulating motor in the two-phase rotating coordinate system according to the torque command, and obtain the motor adjustment model according to the voltage equation;

[0027] S3: Obtain a command signal through space vector pulse width modulation according to the motor adjustment model, and adjust the rotational speed of the inner rotor and the rotational speed of the outer rotor according to the command signal.

[0028] According to a control method for a doubly-fed synchronous wind power generation mechanism provided by the present invention, step S1 includes:

[0029] S11: Measure the rotational speed of the inner rotor and the rotational speed of the outer rotor, and calculate the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding:

[0030]

[0031] where 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;

[0032] S12: Calculate the speed reference value :

[0033] When the electrically excited synchronous generator does not meet the grid connection conditions, the formula is:

[0034]

[0035] where is the synchronous speed of the electrically excited synchronous generator;

[0036] When the electrically excited synchronous generator has met the grid connection conditions, the formula is:

[0037]

[0038] where is the optimal value of the rotational speed of the outer rotor;

[0039] S13: Perform PI adjustment on the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding and the speed reference value to obtain the torque command .

[0040] According to a control method for a doubly-fed synchronous wind power generation mechanism provided by the present invention, step S2 includes:

[0041] S21: Establish the voltage equation of the statorless speed-regulating motor in the two-phase rotating coordinate system as:

[0042]

[0043] Among them, is the voltage component of the inner rotor under the axis, is the resistance of the inner rotor, is the current component of the inner rotor under the axis, is the inductance of the inner rotor under the axis, is the current component of the inner rotor under the axis, is the inductance of the inner rotor under the axis, is the first derivative with respect to time , is the voltage component of the inner rotor under the axis, is the first derivative with respect to time , is the amplitude of the maximum value of the magnetic flux linkage linked by the magnetic field of the outer rotor and each phase winding of the inner rotor;

[0044] At steady state, there is:

[0045] .

[0046] S22: Calculate the current reference value according to the torque command:

[0047]

[0048] Among them, is the number of pole pairs of the statorless speed regulation motor;

[0049] S23: Perform PI regulation according to the voltage equation and torque command to obtain the motor adjustment model:

[0050]

[0051] Among them, is the axis feedforward compensation term, is the proportional coefficient of the current loop, is the integral coefficient of the current loop.

[0052] One or more of the above technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0053] A dual-fed synchronous wind power generating mechanism and its control method provided by the present invention are composed of mature motor components such as a permanent magnet outer rotor, a wound inner rotor, and an electrically excited synchronous generator in a dual-fed synchronous wind power generation system, which can solve the problems of difficult processing of components and difficult technology popularization in existing speed-regulated wind turbines. Secondly, in this system, only the statorless speed-regulated motor requires a converter matching its power, while the synchronous generator does not require a converter, that is, it belongs to a partial power converter unit, which can solve the problem of large converter power in existing speed-regulated wind turbines. Finally, the decoupling control strategy of the statorless speed-regulated motor operating at variable speed and constant frequency within the full wind speed range can solve the problem of low power generation efficiency in existing speed-regulated wind turbines.

[0054] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0055] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0056] Figure 1 It is a schematic structural diagram of a dual-fed synchronous wind power generating mechanism provided by the present invention.

[0057] Figure 2 It is a schematic flow diagram of a control method for a dual-fed synchronous wind power generating mechanism provided by the present invention.

[0058] Figure 3 It is a structural block diagram of a control method for a dual-fed synchronous wind power generating mechanism provided by the present invention.

[0059] Reference Signs:

[0060] 1, wind turbine; 2, speed increasing gearbox; 3, statorless speed-regulated 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 Embodiments

[0061] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. The following embodiments are used to illustrate the present invention, but shall not be used to limit the scope of the present invention.

[0062] 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 "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0063] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without conflict, those skilled in the art can combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0064] The following will describe the present invention in conjunction with Figures 1 to 3 Describe the present invention.

[0065] Embodiment

[0066] As Figure 1 shown, Figure 1 is a schematic structural diagram of a doubly-fed synchronous wind power generation mechanism provided by the present invention. Among them, it includes: a wind turbine 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.

[0067] The statorless speed-regulating motor 3 includes an outer rotor 9 and an inner rotor 10;

[0068] The wind turbine 1 is connected to the input end of the speed-increasing gearbox 2;

[0069] The output end of the speed-increasing gearbox 2 is connected to the outer rotor 9;

[0070] One end of the converter is connected to the inner rotor 10;

[0071] The other end of the converter is connected to the first input terminal of the transformer 8;

[0072] The first end of the electrically excited synchronous generator 4 is connected to the inner rotor 10;

[0073] The second end of the electrically excited synchronous generator 4 is connected to the input terminal of the inverter 6;

[0074] The third end of the electrically excited synchronous generator 4 is connected to one end of the main switch 7;

[0075] The output terminal of the inverter 6 is connected to the second input terminal of the transformer 8;

[0076] The other end of the main switch 7 is connected to the power grid;

[0077] The output terminal of the transformer 8 is connected to the power grid.

[0078] Specifically, the converter is a back-to-back dual PWM converter 5.

[0079] The wind turbine 1 is mechanically connected to the speed increaser gearbox 2 through a low-speed shaft. The wind energy absorbed by the wind turbine 1 is converted into mechanical energy and then transmitted to the speed increaser gearbox 2. After one-stage speed increase by the speed increaser gearbox 2, the high-speed shaft of the speed increaser 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-type inner rotor of the statorless speed-regulating motor is electrically connected to the power 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 power grid or sends electric energy to the power grid through the converter, realizing the bidirectional electric energy exchange between the statorless speed-regulating motor 3 and the power grid.

[0080] While the rotor of the EESG is mechanically connected to the inner rotor 10 of the statorless speed-regulating motor through a synchronous shaft, it is electrically connected to an excitation device to regulate the reactive power of the system. The stator of the EESG is connected to the power grid through a main switch. Before the EESG meets the grid connection conditions, the main switch is in the off state. The system only exchanges energy with the power grid through the statorless speed-regulating motor. The control objective 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 closes, and the EESG converts the mechanical energy transmitted through the synchronous shaft by the statorless speed-regulating motor into electrical energy and then 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 dual-path energy exchange with the power grid through a converter connected to the wound-type 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 the EESG is connected to the grid, the control objective of the statorless speed-regulating motor is that the speed of the outer rotor tracks the optimal speed corresponding to the maximum power point of the wind turbine at different wind speeds so as to capture the maximum wind energy.

[0081] Specifically, the wind turbine 1 is mechanically connected to the speed increaser 2 through a low-speed shaft, the speed increaser 2 is mechanically connected to the outer rotor 9 through a high-speed shaft, and the inner rotor 10 is mechanically connected to the rotor of the electrically excited synchronous generator 4 through a synchronous shaft.

[0082] The outer rotor speed of the statorless speed-regulating motor is , and the inner rotor speed is . The rotational magnetic field speed formed by the alternating current with a frequency of on the inner rotor winding is . According to the electromechanics principle that energy exchange can only occur 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:

[0083]

[0084] When , takes a positive value, and the rotational magnetic field speed formed by the excitation current of the inner rotor winding is in the same direction as the speeds of the inner and outer rotors; conversely, takes a negative value, and the rotational magnetic field speed is in the opposite direction to the speeds of the inner and outer rotors.

[0085] 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:

[0086]

[0087] In the formula, is the number of pole pairs of the statorless speed-regulating motor. Changing the frequency of the excitation current of the inner rotor winding Adjustable 。

[0088] The positive direction of the statorless speed-regulating motor is defined according to the generator convention. The rotational speed is positive in the counterclockwise direction, the torque is positive in the clockwise direction, the mechanical power is positive when input to the statorless speed-regulating motor, and the electromagnetic power is positive when output from the statorless speed-regulating motor.

[0089] 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 inner 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:

[0090]

[0091] Wherein, 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 , there are the following relationships: , , is the electrical angular velocity of the outer rotor, is the electrical angular velocity of the inner rotor, is the derivative with respect to time.

[0092] When the speed of the outer rotor is stable, there is . When the speed of the inner rotor is stable, there is . Since the electromagnetic torques on the inner and outer rotors are equal in magnitude and opposite in direction, i.e., , therefore, when the speed of the statorless speed-regulating motor is stable, the torque relationship is:

[0093]

[0094] When the speed of the statorless speed-regulating motor is stable, the mechanical torques of its inner and outer rotors are equal in magnitude and opposite in direction.

[0095] When the positive direction of the statorless speed-regulating motor is defined according to the generator convention, its power relationship is:

[0096]

[0097] 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 as the input, is the mechanical power of the inner rotor of the statorless speed-regulating motor as the input.

[0098] The relationships among the speed, torque, and power of the statorless speed-regulating motor are as follows:

[0099]

[0100] Since the positive direction of the statorless speed-regulating motor is defined according to the generator convention, and in the actual power flow direction, the mechanical power of the outer rotor of the statorless speed-regulating motor always flows into the statorless speed-regulating motor, and the mechanical power of the inner rotor of the statorless speed-regulating motor always flows out of the statorless speed-regulating motor.

[0101] Specifically, the double-fed synchronous wind power generation mechanism described has three operating states: sub-synchronous operating state, super-synchronous operating state, and synchronous operating state.

[0102] Sub-synchronous operating state: The speed of the outer rotor of the statorless speed-regulating motor is lower than the speed of the inner rotor, that is , when it is in the sub-synchronous operating state. The rotational magnetic field speed is opposite to the specified positive direction, and is in the clockwise direction. is the same as the specified positive direction, and is in the clockwise direction; is opposite to the specified positive direction, and is in the counterclockwise direction; the two are equal in magnitude and opposite in direction, . is the same as the specified positive direction, , indicating that there is mechanical power input to the statorless speed-regulating motor; is opposite to the specified positive direction, , indicating that there is mechanical power output from the statorless speed-regulating motor; is opposite to the specified positive direction, , indicating that there is electromagnetic power input to the statorless speed-regulating motor. Therefore, the statorless speed-regulating motor absorbs electrical energy from the power grid through the converter, converts the electrical energy into mechanical energy through the synchronous shaft, and assists the electrically excited synchronous generator in generating electricity.

[0103] Super-synchronous operating state: The speed of the outer rotor of the statorless speed-regulating motor is higher than the speed of the inner rotor, that is , , and it is in the super-synchronous operating state. is the same as the specified positive direction, , and is in the counterclockwise direction. is the same as the specified positive direction, , and is in the clockwise direction; Opposite to the specified positive direction, it is the counterclockwise direction; the two are equal in magnitude and opposite in direction, . Same as the specified positive direction, which indicates that there is mechanical power input to the statorless speed-regulating motor; Opposite to the specified positive direction, which indicates that there is mechanical power output from the statorless speed-regulating motor; Same as the specified positive direction, which indicates that there is electromagnetic power output from the statorless speed-regulating motor. The statorless speed-regulating motor generates electric energy to the power grid through an inverter to assist the electrically excited synchronous generator in generating electricity.

[0104] 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, it is the clockwise direction; Opposite to the specified positive direction, it is the counterclockwise direction; the two are equal in magnitude and opposite in direction, . Same as the specified positive direction, which indicates that there is mechanical power input to the statorless speed-regulating motor; Opposite to the specified positive direction, which indicates that there is mechanical power output from the statorless speed-regulating motor; which indicates that there is no active power exchange between the statorless speed-regulating motor and the power grid.

[0105] Specifically, as Figure 2 shown, the present invention also provides a control method for a doubly-fed synchronous wind power generation mechanism, including:

[0106] S1: Measure the speed of the inner rotor and the speed of the outer rotor, and calculate the speed reference value; obtain the 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;

[0107] S2: According to the torque command, establish the voltage equation of the statorless speed-regulating motor in the two-phase rotating coordinate system, and obtain the motor adjustment model according to the voltage equation;

[0108] S3: Obtain the command signal through space vector pulse width modulation according to the motor adjustment model, and adjust the speed of the inner rotor and the speed of the outer rotor according to the command signal.

[0109] Specifically, step S1 includes:

[0110] S11: Measure the rotational speeds of the inner rotor and the outer rotor, and calculate the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding:

[0111]

[0112] Where, 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;

[0113] S12: Calculate the rotational speed reference value :

[0114] When the electrically excited synchronous generator does not meet the grid connection conditions, the formula is:

[0115]

[0116] Where, is the synchronous rotational speed of the electrically excited synchronous generator;

[0117] When the electrically excited synchronous generator has met the grid connection conditions, the formula is:

[0118]

[0119] Where, is the optimal value of the rotational speed of the outer rotor;

[0120] S13: Perform PI regulation on the electrical angular velocity of the rotating magnetic field formed by the alternating current on the inner rotor winding and the rotational speed reference value to obtain the torque command .

[0121] Specifically, step S2 includes:

[0122] S21: Establish the voltage equation of the statorless speed regulation motor in the two-phase rotating coordinate system as:

[0123]

[0124] Where, is the voltage component of the inner rotor under the axis, is the resistance of the inner rotor, is the current component of the inner rotor under the axis, is the inductance of the inner rotor under the axis, is the current component of the inner rotor under the axis, is the inductance of the inner rotor under the axis, is the first derivative with respect to time , and is the voltage component of the inner rotor under the axis; is the first derivative with respect to time , and is the amplitude of the maximum value of the magnetic linkage linked by the magnetic field of the outer rotor and each phase winding of the inner rotor;

[0125] At steady state, there is:

[0126] ;

[0127] S22: Calculate the current reference value according to the torque command:

[0128]

[0129] wherein, is the number of pole pairs of the statorless speed regulation motor;

[0130] S23: Perform PI regulation according to the voltage equation and torque command to obtain the motor adjustment model:

[0131]

[0132] wherein, is the proportional coefficient of the current loop, is the integral coefficient of the current loop.

[0133] As Figure 3 shown, Figure 3 is the structural block diagram of a control method for a doubly-fed synchronous wind power generation mechanism provided by the present invention. The rotational speed of the inner rotor of the statorless speed regulation motor and the rotational speed of the outer rotor are respectively detected, and after taking the difference, it is compared with the reference value to form a speed outer loop. After the speed deviation passes through the PI regulator, the axis current reference value is obtained. The axis current reference value is 0, that is, , and they are respectively compared with the actual values to form a current inner loop. After the current deviation passes through the PI regulator, and are obtained. After superimposing the cross-coupling voltage, and are obtained. The axis voltage value passes through transformation to obtain the axis component voltage and Axis component voltage , the drive signal of the inner rotor side converter is obtained through space vector control (SVPWM, Space Vector Pulse Width Modulation).

[0134] The current of the inner rotor side converter passes through transformation to obtain and which are fed back to steps S1 and S2 for further adjustment. After the statorless speed-regulating motor undergoes space vector control, by measuring the inner rotor position angle and the outer rotor position angle of the statorless speed-regulating motor, the difference between the inner rotor position and the outer rotor position is calculated. By measuring the electrical angular velocity of the outer rotor and the electrical angular velocity of the inner rotor, the difference between the outer rotor electrical angular velocity and the inner rotor electrical angular velocity is calculated. Then and are fed back to steps S1 and S2 for further adjustment.

[0135] The present invention is committed to solving the problems existing in the existing speed-regulating wind turbines, such as difficult component processing, difficult technology promotion, large converter power, and low power generation efficiency. First, the doubly-fed synchronous wind power generation system designed by the present invention is composed of mature motor components such as a permanent magnet outer rotor, a wound inner rotor, and an electrically excited synchronous generator, which can solve the problems of difficult component processing and difficult technology promotion in the existing speed-regulating wind turbines. Second, only the statorless speed-regulating motor in this system requires a converter matching its power, while the synchronous generator does not require a converter, that is, it belongs to a partial power converter unit, which can solve the problem of large converter power in the existing speed-regulating wind turbines. Finally, the decoupling control strategy of the statorless speed-regulating motor operating at variable speed and constant frequency within the full wind speed range can solve the problem of low power generation efficiency in the existing speed-regulating wind turbines.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0137] It should be noted that the embodiments of the present disclosure can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by a suitable instruction execution system such as a microprocessor or dedicated design hardware. Those skilled in the art can understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code is provided on a programmable memory or a data carrier such as an optical or electronic signal carrier.

[0138] In addition, although the operations of the method of the present disclosure are described in a specific order in the drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. On the contrary, the order of execution of the steps depicted in the flowchart can be changed. Additionally or alternatively, certain 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 one device described above can be further divided and embodied by multiple devices.

[0139] 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 aims to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A control method for a doubly-fed synchronous wind power generation mechanism, characterized in that: The method is used to control a double-fed synchronous wind power generation mechanism, comprising the following steps: S1: Measure the speed of the inner rotor and the speed of the outer rotor, and calculate the speed reference value; according to the speed of the inner rotor, the speed of the outer rotor and the speed reference value, the torque command is obtained through the PI regulator: 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 ; 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: obtaining a command signal by performing space vector pulse width modulation according to the motor adjustment model, and adjusting the speed of the inner rotor and the speed of the outer rotor according to the command signal; The doubly-fed synchronous wind power generation mechanism comprises: a wind wheel, a speed-increasing gearbox, a statorless speed-regulating motor, an electrically excited synchronous generator, a converter, an inverter and a transformer.

2. A control method for 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. The control method of 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. The control method of 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 control method for 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 control method for 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. The control method of a doubly-fed synchronous wind power generation mechanism according to claim 1, 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 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.

Images