Pitch angle control method and device for variable pitch wind turbine

Abstract

The disclosure provides a pitch angle control method and device of a variable pitch wind turbine, and relates to the technical field of pitch control, which comprises the following steps: in response to detecting that the wind speed reaches a first wind speed, the pitch angle is controlled to keep the rotating speed of the wind turbine within a preset range; in response to determining that the wind turbine has been connected to the grid and detecting that the wind turbine is running at a first rotating speed, based on a preset first control strategy, the wind turbine is controlled to run at variable speed according to the current wind speed, so that the wind turbine reaches an optimal tip speed ratio; in response to determining that the output power of the wind turbine does not reach a rated output power, the pitch angle is controlled to control the wind turbine to run at the first rotating speed; and in response to determining that the wind turbine reaches the rated output power and the wind speed increases, the pitch angle is increased. Thus, the wind energy captured by the wind turbine can be controlled by adjusting the pitch angle, so as to improve the efficiency of the wind turbine and protect the wind turbine.

Description

Technical Field

[0001] This disclosure relates to the field of pitch angle control technology, and in particular to a pitch angle control method and device for a variable pitch wind turbine. Background Technology

[0002] In the wind power industry, variable pitch wind turbines are used to adjust the angle of the blades to adapt to different wind speeds and power demands. Pitch angle control strategies refer to control algorithms and methods that determine the pitch angle based on real-time wind speed and other parameters. Related technologies typically employ constant pitch angle control, achieved by fixing the pitch angle to a constant value. The constant pitch angle is usually set based on the average wind speed or the turbine's rated power. However, this control strategy cannot adapt to changes in wind speed and the optimization of power output. Summary of the Invention

[0003] This disclosure aims to at least partially address one of the technical problems in the related art.

[0004] The first aspect of this disclosure proposes a method for controlling the pitch angle of a variable pitch wind turbine, including:

[0005] In response to the detection that the wind speed has reached the first wind speed, the blade pitch is controlled to keep the speed of the wind turbine unit within a preset range;

[0006] In response to determining that the wind turbine has been connected to the grid and detecting that the wind turbine is operating at a first speed, based on a preset first control strategy, the wind turbine is controlled to operate at variable speed according to the current wind speed so that the wind turbine can achieve the optimal tip speed ratio.

[0007] In response to determining that the output power of the wind turbine has not reached the rated output power, the pitch angle is controlled to control the wind turbine to operate at the first speed.

[0008] In response to determining that the wind turbine has reached the rated output power and the wind speed has increased, the pitch angle is increased.

[0009] A second aspect of this disclosure provides a pitch angle control device for a variable pitch wind turbine, comprising:

[0010] The first control module is used to control the blade pitch in response to the detection that the wind speed has reached a first wind speed, so as to keep the speed of the wind turbine unit within a preset range;

[0011] The second control module is used to respond to determining that the wind turbine has been connected to the grid and detecting that the wind turbine is running at a first speed, and based on a preset first control strategy, control the wind turbine to operate at a variable speed according to the current wind speed so that the wind turbine can achieve the optimal tip speed ratio.

[0012] The third control module is used to control the pitch angle in response to determining that the output power of the wind turbine has not reached the rated output power, so as to control the wind turbine to operate at the first speed.

[0013] The first determining module is configured to increase the pitch angle in response to determining that the wind turbine has reached the rated output power and the wind speed has increased.

[0014] A third aspect of this disclosure provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the pitch angle control method for a variable pitch wind turbine as proposed in the first aspect of this disclosure.

[0015] The fourth aspect of this disclosure provides a non-transitory computer-readable storage medium storing a computer program that, when executed by a processor, implements the pitch angle control method for a variable pitch wind turbine as proposed in the first aspect of this disclosure.

[0016] The pitch angle control method, device, equipment, and storage medium for variable pitch wind turbines disclosed herein have the following beneficial effects:

[0017] In this embodiment, firstly, in response to detecting that the wind speed has reached a first wind speed, the blade pitch is controlled to keep the wind turbine's rotational speed within a preset range. Then, in response to determining that the wind turbine is connected to the grid and detecting that it is operating at the first rotational speed, based on a preset first control strategy and according to the current wind speed, the wind turbine is controlled to operate at variable speeds to achieve the optimal tip speed ratio. Next, in response to determining that the wind turbine's output power has not reached its rated output power, the blade pitch angle is controlled to keep the wind turbine operating at the first rotational speed. Finally, in response to determining that the wind turbine has reached its rated output power and the wind speed increases, the blade pitch angle is increased. Thus, by adjusting the blade pitch angle, the wind energy captured by the wind turbine can be controlled, thereby improving the turbine's efficiency and protecting it.

[0018] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this disclosure will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 This is a flowchart illustrating a pitch angle control method for a variable pitch wind turbine provided in an embodiment of this disclosure.

[0021] Figure 2 A schematic diagram showing the relationship between the output mechanical power and rotational speed of a wind turbine at different wind speeds;

[0022] Figure 3 This is a structural block diagram of a pitch angle control device for a variable pitch wind turbine provided in an embodiment of the present disclosure;

[0023] Figure 4 A block diagram of an exemplary computer device suitable for implementing embodiments of the present disclosure is shown. Detailed Implementation

[0024] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0025] The following description, with reference to the accompanying drawings, outlines a pitch angle control method, apparatus, computer device, and storage medium for a variable pitch wind turbine according to embodiments of the present disclosure.

[0026] It should be noted that the execution subject of the pitch angle control method of the variable pitch wind turbine in the embodiments of this disclosure is the pitch angle control device of the variable pitch wind turbine. This device can be implemented by software and / or hardware and can be configured in any electronic device.

[0027] Figure 1 This is a flowchart illustrating the pitch angle control method for a variable pitch wind turbine provided in the first embodiment of this disclosure.

[0028] like Figure 1 As shown, the pitch angle control method for this variable pitch wind turbine may include the following steps:

[0029] Step 101: In response to detecting that the wind speed has reached the first wind speed, the pitch is controlled to keep the speed of the wind turbine unit within a preset range.

[0030] It should be noted that as the wind speed increases from 0, when it reaches the cut-in wind speed, it enters the start-up zone. At this time, the main task of the wind power generation system is to achieve grid connection control of the generator. The speed of the unit is adjusted by changing the pitch through the pitch system to keep it constant or vary within an allowable range.

[0031] The first wind speed can be a predetermined cut-in wind speed.

[0032] Optionally, a grid connection control method corresponding to the type of wind turbine generator can also be determined, and in response to detecting that the wind speed reaches a first wind speed, the generator is connected to the grid according to the grid connection control method.

[0033] It should be noted that if the wind turbine generator is a permanent magnet synchronous motor with a full-power converter, the stator voltage frequency and amplitude do not need to be the same as the grid voltage during grid connection, since the converter provides electrical isolation. When the wind speed reaches the first wind speed, i.e., the cut-in wind speed, the active power captured by the wind turbine can offset the losses of the wind power generation system, thus achieving grid connection.

[0034] Step 102: In response to determining that the wind turbine has been connected to the grid and detecting that the wind turbine is running at the first speed, based on the preset first control strategy and according to the current wind speed, the wind turbine is controlled to operate at variable speed so that the wind turbine can achieve the optimal tip speed ratio.

[0035] It should be noted that if the wind turbine is already connected to the grid and operating at its maximum speed, the turbine pitch angle is in a constant pitch operation state without adjustment. In this area, variable speed operation with maximum wind energy tracking is implemented, and the wind turbine's speed changes accordingly with the wind speed to achieve the optimal tip speed ratio, thus ensuring that the wind energy utilization coefficient of the turbine remains at its maximum value.

[0036] Optionally, a mapping relationship corresponding to the current wind speed can be determined first, wherein the mapping relationship is the mapping relationship between the wind turbine output mechanical power and the wind turbine rotation speed. Then, the target rotation speed corresponding to the maximum wind turbine output mechanical power can be determined, and then the wind turbine can be controlled to operate at the target rotation speed corresponding to the current wind speed, so that the wind turbine can achieve the optimal tip speed ratio.

[0037] The relationship between the wind turbine output power Po and the rotational speed ωw under different wind speeds v1>v2>v3 is as follows: Figure 2 As shown, the output power varies at different turbine speeds for the same wind speed. There exists an optimal speed at the same wind speed, where the wind turbine achieves the best tip speed ratio, capturing the maximum energy and outputting the maximum power at that wind speed. Therefore, maximum energy tracking (MAT) control of a wind turbine is closely related to its speed control. Thus, by effectively controlling the generator speed, the wind turbine can operate at the optimal speed corresponding to a given wind speed, achieving the best tip speed ratio and maximum power output.

[0038] Optionally, before determining the mapping relationship corresponding to the current wind speed, the method further includes:

[0039] Determine the wind turbine coefficient corresponding to the wind turbine unit;

[0040] Calculate the wind turbine output mechanical power corresponding to the wind turbine speed based on the wind turbine rotation speed and the wind turbine coefficient.

[0041] Figure 2 This diagram illustrates the relationship between the output mechanical power and rotational speed of a wind turbine under different wind speeds. Wind turbines operating along the Popt curve will obtain the maximum wind energy and output the maximum mechanical power Pmax.

[0042]

[0043] k w =0.5ρS w (R w / λ opt )'C pmaX

[0044]

[0045] Where β is the blade pitch angle, ωt is the wind turbine angular frequency, λ is the tip speed ratio, Cp can be the wind energy utilization coefficient, R is the wind turbine radius, kW is the wind turbine coefficient, ωw is the wind turbine speed, and ρ is the wind power density.

[0046] For direct-drive fans, the maximum mechanical power is proportional to the cube of the mechanical speed of the permanent magnet synchronous motor, that is, the cube of ωw.

[0047] Step 103: In response to determining that the output power of the wind turbine has not reached the rated output power, the pitch angle is controlled to control the wind turbine to operate at the first speed.

[0048] It should be noted that if the wind turbine has reached its maximum speed, but the output power of the wind turbine has not yet reached its rated output, in order to protect the unit from overload, maximum wind energy tracking will no longer be performed. Instead, the pitch angle will be adjusted through the pitch control of the wind turbine control subsystem to ensure constant speed power generation at the maximum permissible speed.

[0049] Step 104: In response to determining that the wind turbine has reached its rated output power and the wind speed has increased, increase the pitch angle.

[0050] It should be noted that as wind speed increases, the output mechanical power of the wind turbine continuously increases, until the generator reaches its power limit, i.e., its rated output power. At this point, it is necessary to control the unit's output power to ensure it does not exceed the rated value, and the wind turbine operates in a constant speed and constant power state. Constant power control in this region is achieved by controlling the blade pitch angle; that is, as wind speed increases, the blade pitch angle is increased to rapidly reduce the wind energy utilization coefficient, thereby ensuring constant power.

[0051] Optionally, if the actual wind speed is higher than the wind speed required for the wind turbine's rated power, the wind turbine blades will adjust their pitch to limit the mechanical power delivered to the shaft to the wind turbine's rated power value. When the actual wind speed is lower than the wind speed required for the wind turbine's rated power, the blades will be set to the minimum pitch to maximize mechanical power.

[0052] Optionally, the device can set the wind turbine blades to a minimum pitch in response to detecting a wind speed lower than a second wind speed, wherein the second wind speed characterizes the wind speed required for the wind turbine to reach the rated output power.

[0053] Alternatively, the device may, in response to detecting that the wind speed is higher than the second wind speed, control the wind turbine blades to pitch, setting the current mechanical power delivered to the shaft as the rated output power.

[0054] In this embodiment, firstly, in response to detecting that the wind speed has reached a first wind speed, the blade pitch is controlled to keep the wind turbine's rotational speed within a preset range. Then, in response to determining that the wind turbine is connected to the grid and detecting that it is operating at the first rotational speed, based on a preset first control strategy and according to the current wind speed, the wind turbine is controlled to operate at variable speeds to achieve the optimal tip speed ratio. Next, in response to determining that the wind turbine's output power has not reached its rated output power, the blade pitch angle is controlled to keep the wind turbine operating at the first rotational speed. Finally, in response to determining that the wind turbine has reached its rated output power and the wind speed increases, the blade pitch angle is increased. Thus, by adjusting the blade pitch angle, the wind energy captured by the wind turbine can be controlled, thereby improving the turbine's efficiency and protecting it.

[0055] To achieve the above embodiments, this disclosure also proposes a pitch angle control device for a variable pitch wind turbine.

[0056] Figure 4 This is a structural block diagram of the pitch angle control device for a variable pitch wind turbine provided in the third embodiment of this disclosure.

[0057] like Figure 4 As shown, the pitch angle control device 400 of the variable pitch wind turbine may include:

[0058] The first control module 310 is used to control the pitch of the blade in response to the detection that the wind speed has reached a first wind speed, so as to keep the speed of the wind turbine unit within a preset range.

[0059] The second control module 320 is used to respond to determining that the wind turbine has been connected to the grid and detecting that the wind turbine is running at a first speed, and based on a preset first control strategy, control the wind turbine to operate at a variable speed according to the current wind speed so that the wind turbine can achieve the optimal tip speed ratio.

[0060] The third control module 330 is used to control the pitch angle in response to determining that the output power of the wind turbine has not reached the rated output power, so as to control the wind turbine to operate at the first speed.

[0061] The first determining module 340 is configured to increase the pitch angle in response to determining that the wind turbine has reached the rated output power and the wind speed has increased.

[0062] Optionally, the device may also include:

[0063] A first detection module is used to set the wind turbine blades to the minimum pitch in response to detecting that the wind speed is lower than a second wind speed, wherein the second wind speed represents the wind speed required for the wind turbine to reach the rated output power.

[0064] or,

[0065] The second detection module is used to control the wind turbine blades to pitch in response to the detection that the wind speed is higher than the second wind speed, so as to set the rated output power with the mechanical power currently delivered to the shaft.

[0066] Optionally, the second control module includes:

[0067] The first determining unit is used to determine the mapping relationship corresponding to the current wind speed, wherein the mapping relationship is the mapping relationship between the wind turbine output mechanical power and the wind turbine rotation speed;

[0068] The second determining unit is used to determine the target rotational speed corresponding to the maximum output mechanical power of the wind turbine;

[0069] The control unit is used to control the wind turbine to operate at the target speed corresponding to the current wind speed, so that the wind turbine can achieve the optimal tip speed ratio.

[0070] Optionally, the first determining unit is further configured to:

[0071] Determine the wind turbine coefficient corresponding to the wind turbine unit;

[0072] Calculate the wind turbine output mechanical power corresponding to the wind turbine speed based on the wind turbine rotation speed and the wind turbine coefficient.

[0073] Optionally, the device may also include:

[0074] The second determining module is used to determine the grid connection control mode corresponding to the type of the wind turbine generator;

[0075] The fourth control module is used to control the generator to connect to the grid in accordance with the grid connection control method when the wind speed is detected to reach the first wind speed.

[0076] In this embodiment, firstly, in response to detecting that the wind speed has reached a first wind speed, the blade pitch is controlled to keep the wind turbine's rotational speed within a preset range. Then, in response to determining that the wind turbine is connected to the grid and detecting that it is operating at the first rotational speed, based on a preset first control strategy and according to the current wind speed, the wind turbine is controlled to operate at variable speeds to achieve the optimal tip speed ratio. Next, in response to determining that the wind turbine's output power has not reached its rated output power, the blade pitch angle is controlled to keep the wind turbine operating at the first rotational speed. Finally, in response to determining that the wind turbine has reached its rated output power and the wind speed increases, the blade pitch angle is increased. Thus, by adjusting the blade pitch angle, the wind energy captured by the wind turbine can be controlled, thereby improving the turbine's efficiency and protecting it.

[0077] To implement the above embodiments, this disclosure also proposes a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the pitch angle control method for a variable pitch wind turbine as proposed in the foregoing embodiments of this disclosure.

[0078] To implement the above embodiments, this disclosure also proposes a non-transitory computer-readable storage medium storing a computer program, which, when executed by a processor, implements the pitch angle control method for a variable pitch wind turbine as proposed in the foregoing embodiments of this disclosure.

[0079] To implement the above embodiments, this disclosure also proposes a computer program product that, when the instruction processor in the computer program product is executed, performs the pitch angle control method for a variable pitch wind turbine as proposed in the foregoing embodiments of this disclosure.

[0080] Figure 4 A block diagram of an exemplary computer device suitable for implementing embodiments of the present disclosure is shown. Figure 4 The computer device 12 shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments disclosed herein.

[0081] like Figure 4 As shown, the computer device 12 is represented in the form of a general-purpose computing device. The components of the computer device 12 may include, but are not limited to: one or more processors or processing units 16, system memory 28, and a bus 18 connecting different system components (including system memory 28 and processing unit 16).

[0082] Bus 18 represents one or more of several bus architectures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any of the various bus architectures. Examples of these architectures include, but are not limited to, the Industry Standard Architecture (ISA) bus, the Micro Channel Architecture (MAC) bus, the Enhanced ISA bus, the Video Electronics Standards Association (VESA) local bus, and the Peripheral Component Interconnect (PCI) bus.

[0083] Computer device 12 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by computer device 12, including volatile and non-volatile media, removable and non-removable media.

[0084] Memory 28 may include computer system readable media in the form of volatile memory, such as Random Access Memory (RAM) 30 and / or cache memory 32. Computer device 12 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 34 may be used to read and write non-removable, non-volatile magnetic media (…). Figure 4 Not shown; usually referred to as a "hard drive"). Although Figure 4 Not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk") and an optical disc drive for reading and writing to a removable non-volatile optical disc (e.g., a compact disc read-only memory (CD-ROM), a digital video disc read-only memory (DVD-ROM), or other optical media) may be provided. In these cases, each drive may be connected to bus 18 via one or more data media interfaces. Memory 28 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of this disclosure.

[0085] A program / utility 40 having a set (at least one) of program modules 42 may be stored, for example, in memory 28. Such program modules 42 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment. Program modules 42 typically perform the functions and / or methods described in the embodiments of this disclosure.

[0086] Computer device 12 can also communicate with one or more external devices 14 (e.g., keyboard, pointing device, display 24, etc.), and with one or more devices that enable a user to interact with computer device 12, and / or with any device that enables computer device 12 to communicate with one or more other computing devices (e.g., network card, modem, etc.). This communication can be performed via input / output (I / O) interface 22. Furthermore, computer device 12 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via network adapter 20. As shown, network adapter 20 communicates with other modules of computer device 12 via bus 18. It should be understood that, although not shown in the figures, other hardware and / or software modules can be used in conjunction with computer device 12, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0087] The processing unit 16 executes various functional applications and data processing by running programs stored in the system memory 28, such as implementing the methods mentioned in the foregoing embodiments.

[0088] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0089] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0090] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of this disclosure includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of this disclosure pertain.

[0091] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0092] It should be understood that various parts of this disclosure can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0093] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0094] Furthermore, the functional units in the various embodiments of this disclosure can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0095] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A method for controlling the pitch angle of a variable pitch wind turbine, characterized in that, include: In response to the detection that the wind speed has reached the first wind speed, and the wind turbine generator is a permanent magnet synchronous motor with a full-power converter, the generator is connected to the grid in a way that the stator voltage frequency and amplitude do not need to be synchronized with the grid, and the pitch is controlled so that the speed of the wind turbine is kept within the preset range. In response to determining that the wind turbine has been connected to the grid and detecting that the wind turbine is operating at a first speed, a mapping relationship corresponding to the current wind speed is determined, wherein the mapping relationship is a mapping relationship between the wind turbine output mechanical power and the wind turbine speed; Determine the target rotational speed corresponding to the maximum output mechanical power of the fan; The wind turbine is controlled to operate at the target rotational speed corresponding to the current wind speed, so that the wind turbine achieves the optimal tip speed ratio. In response to determining that the output power of the wind turbine has not reached the rated output power, the pitch angle is controlled to control the wind turbine to operate at the first speed. When the wind turbine reaches the maximum speed and the output power of the wind turbine has not reached the rated output state, the pitch angle is adjusted to ensure that the wind turbine operates at a constant speed. In response to determining that the wind turbine has reached the rated output power and the wind speed has increased, the pitch angle is increased to reduce the wind energy utilization coefficient, ensuring that the wind turbine enters a constant power operation state; The method further includes: In response to detecting that the wind speed is lower than a second wind speed, the wind turbine blades are set to the minimum pitch, wherein the second wind speed represents the wind speed required for the wind turbine to reach the rated output power; or... In response to detecting that the wind speed is higher than the second wind speed, the wind turbine blades are controlled to pitch, and the mechanical power currently delivered to the shaft is set as the rated output power; Determine the grid connection control method corresponding to the type of the wind turbine generator; In response to the detection that the wind speed has reached the first wind speed, the generator is connected to the grid according to the grid connection control method.

2. The method according to claim 1, characterized in that, Before determining the mapping relationship corresponding to the current wind speed, the method further includes: Determine the wind turbine coefficient corresponding to the wind turbine unit; Calculate the wind turbine output mechanical power corresponding to the wind turbine speed based on the wind turbine rotation speed and the wind turbine coefficient.

3. A pitch angle control device for a variable pitch wind turbine, characterized in that, include: The first control module is used to respond to the detection that the wind speed has reached the first wind speed and the wind turbine generator is a permanent magnet synchronous motor with a full power converter. It controls the generator to be connected to the grid in a way that the stator voltage frequency and amplitude do not need to be synchronized with the grid, and controls the pitch of the blade to keep the speed of the wind turbine generator within the preset range. The second control module is used to respond to determining that the wind turbine has been connected to the grid and detecting that the wind turbine is running at a first speed, and based on a preset first control strategy, control the wind turbine to operate at a variable speed according to the current wind speed so that the wind turbine can achieve the optimal tip speed ratio. The third control module is used to control the pitch angle in response to determining that the output power of the wind turbine has not reached the rated output power, so as to control the wind turbine to operate at the first speed. When the wind turbine reaches the maximum speed and the output power of the wind turbine has not reached the rated output state, the pitch angle is adjusted to ensure that the wind turbine operates at a constant speed. The first determining module is used to increase the pitch angle to reduce the wind energy utilization coefficient in response to determining that the wind turbine has reached the rated output power and the wind speed has increased, thereby ensuring that the wind turbine enters a constant power operation state. The second control module includes: The first determining unit is used to determine the mapping relationship corresponding to the current wind speed, wherein the mapping relationship is the mapping relationship between the wind turbine output mechanical power and the wind turbine rotation speed; The second determining unit is used to determine the target rotational speed corresponding to the maximum output mechanical power of the wind turbine; The control unit is used to control the wind turbine to operate at the target speed corresponding to the current wind speed, so that the wind turbine can achieve the optimal tip speed ratio. The device further includes: A first detection module is configured to, in response to detecting that the wind speed is lower than a second wind speed, set the wind turbine blades to the minimum pitch, wherein the second wind speed represents the wind speed required for the wind turbine to reach the rated output power; or... The second detection module is used to control the wind turbine blades to pitch in response to the detection that the wind speed is higher than the second wind speed, and set the current mechanical power delivered to the shaft as the rated output power; The second determining module is used to determine the grid connection control mode corresponding to the type of the wind turbine generator; The fourth control module is used to control the generator to connect to the grid in accordance with the grid connection control method when the wind speed is detected to reach the first wind speed.

4. The apparatus according to claim 3, characterized in that, The first determining unit is further configured to: Determine the wind turbine coefficient corresponding to the wind turbine unit; Calculate the wind turbine output mechanical power corresponding to the wind turbine speed based on the wind turbine rotation speed and the wind turbine coefficient.

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