Filtering dust removal system of wind driven generator and control method

Abstract

The invention discloses a filtering dust removal system of a wind driven generator and a control method, and belongs to the technical field of wind power generation. The system comprises a machine base, a generator winding is installed in the machine base, and at least one set of first filtering device is arranged on the machine base; the cooling assembly comprises a cooling shell installed on the machine base, a cooling fan and a second filtering device, the cooling fan and the second filtering device are installed in the cooling shell, an air inlet and an air outlet are formed in the side, away from the machine base, of the cooling shell, and the cooling fan is a reversible axial flow fan; the control unit is used for controlling the filtering dust removal system to be switched between a cooling mode and a dust removal mode; in the cooling mode, the cooling fan is controlled to rotate forwards, and external air enters the machine base through the first filtering device and is exhausted along an air inlet and an air outlet of the cooling shell; in the dust removal mode, the cooling fan is controlled to rotate reversely, and external air enters the base through the air inlet and outlet of the cooling shell and is discharged along the first filtering device of the base.

Description

Technical Field

[0001] The present invention relates to the field of wind turbines, and in particular to a filtering and dust removal structure and a control method for a wind turbine. Background Art

[0002] Doubly-fed induction generators (DFIGs) have long been a mainstream technology in the wind power generation sector. Their stator windings are directly connected to the grid, while their rotor windings are connected via a back-to-back converter. This allows the generator to operate at variable speeds within a certain range around its rated speed, effectively capturing wind energy while also providing reactive power support and fault ride-through capability to the grid. Wind turbines generate significant heat during operation. If this heat is not dissipated promptly and effectively, it can cause the internal temperature of the generator to rise sharply. Currently, DFIGs typically use an open direct cooling system. This involves drawing cooling air directly from the generator's external environment, pressurizing it with an internal cooling fan, and forcing it through heat-generating components within the generator, such as the rotor winding ends and stator core air ducts, to remove heat before dissipating it directly to the external environment.

[0003] The most significant impact of open-type direct cooling on generators is its significant reduction in protection levels. This is particularly true for impurities and dust from the external air, which can easily enter the generator interior, significantly impacting the creepage distances between insulation and internal components. To address this issue, these generators currently incorporate filters at the air inlet to filter out dust, flying catkins, and other impurities. In open-type direct cooling generators, the air inlet filters are disposable and require replacement every six months or a year. In wind farms with harsh environments such as sandstorms and dust, replacement is even more frequent. Otherwise, the filters will become severely clogged with dust and flying catkins, resulting in insufficient airflow and poor cooling, which in turn causes the generator windings to shut down due to high temperatures, limiting the unit's effective power generation time. Furthermore, for safety reasons, during high winds, maintenance personnel are unable to access the tower to clean or replace the filters. This results in the generator windings shutting down due to high temperatures due to filter blockage, rendering the unit inoperable and severely impacting power generation. Therefore, providing a method for accurately determining filter blockage and efficiently removing dust from the filters is a technical problem urgently needed by those skilled in the art. Summary of the Invention

[0004] To this end, the present invention provides a filtering and dust removal system and a control method for a wind turbine, which can automatically and efficiently remove dust from the filter screen of the wind turbine generator set.

[0005] In view of the above technical problems, the present invention provides the following technical solutions:

[0006] A filtering and dust removal system for a wind turbine generator comprises: a machine base, wherein a generator winding is installed inside the machine base, and at least one first filtering device is provided on the machine base; a cooling assembly comprises: a cooling shell installed on the machine base, and a cooling fan and a second filtering device installed in the cooling shell, wherein the cooling shell is provided with an air inlet and outlet on a side away from the machine base, and the cooling fan is a reversible axial flow fan; a control unit, wherein the control unit controls the filtering and dust removal system to switch between a cooling mode and a dust removal mode; in the cooling mode, the cooling fan is controlled to rotate forward, and external air enters the machine base through the first filtering device and is discharged along the air inlet and outlet of the cooling shell; in the dust removal mode, the cooling fan is controlled to rotate backward, and external air enters the interior of the machine base through the air inlet and outlet of the cooling shell and is discharged along the first filtering device of the machine base.

[0007] In some embodiments of the present invention, the wind turbine generator is a doubly-fed induction generator, and in the dust removal mode, the control unit controls the transmission chain of the wind turbine generator to reverse.

[0008] In some embodiments of the present invention, the generator winding includes a stator winding and a rotor winding, the rotor winding is installed on the rotor shaft, and the cooling assembly also includes at least one group of coaxial fans connected to the rotor shaft, and the coaxial fans rotate synchronously with the rotor winding.

[0009] In some embodiments of the present invention, the cooling housing includes an air guide tube extending in the same direction as the rotor shaft, and the cooling fan and the second filter device are installed in the air guide tube.

[0010] In some embodiments of the present invention, the second filter device is an electric shutter-type filter device. In cooling mode, the second filter device is controlled to be in a state of fully opening the air inlet and outlet; in dust removal mode, the second filter device is controlled to be in a state of at least partially blocking the air inlet and outlet.

[0011] In some embodiments of the present invention, a dust concentration sensor and / or an air flow rate sensor is provided in an area of ​​the base close to the first filter device; a winding temperature sensor is provided in an area of ​​the base close to the generator winding.

[0012] In some embodiments of the present invention, the cooling fan has a frequency conversion module. In the dust removal mode, the control unit controls the frequency conversion module of the cooling fan to output periodic pulses.

[0013] The present invention also provides a control method for a wind turbine, comprising:

[0014] Determine whether the first filter device is clogged according to the operating status of the generator set and the air flow conditions near the first filter device;

[0015] If the first filter device is clogged, the dust removal mode is started after the generator set is detected to be shut down. The dust removal mode includes controlling the generator set transmission chain and the cooling fan to reverse so that external air enters the base through the air inlet and outlet of the cooling shell and is discharged along the first filter device of the base.

[0016] In some embodiments of the present invention, determining whether the first filter device is blocked based on the operating state of the generator set and the air flow condition near the first filter device includes:

[0017] If the difference between the real-time power and the full power of the generator set is less than or equal to a first threshold, determining whether the temperature rise of the generator winding exceeds a second threshold; if the temperature rise of the generator winding exceeds the second threshold, determining that the first filter device is clogged;

[0018] If the difference between the real-time power and full power of the unit is greater than the first threshold, the dust concentration and air flow rate in the area where the first filter device is located are judged. If the dust concentration exceeds the third threshold and the air flow rate is lower than the fourth threshold, it is judged that the first filter device is blocked.

[0019] In some embodiments of the present invention, controlling the reverse rotation of the generator set drive chain and the cooling fan in the dust removal mode includes:

[0020] Controlling the variable pitch system of the unit to open the propeller at a negative angle, and controlling the generator to operate near the synchronous speed;

[0021] The frequency conversion module controlling the cooling fan cycles periodically n times in a pulse mode, wherein the pulse mode includes: increasing the power frequency from the first frequency f1 to the second frequency f2 at a first speed v1 and maintaining it for a first time length t1; decreasing the power frequency from the second frequency f2 to the first frequency f1 at a second speed v2 and maintaining it for a second time length t2; wherein v2 < v1, t1 > t2.

[0022] The technical solution of the present invention has the following technical effects compared with the prior art:

[0023] In the wind turbine filtration and dust removal system provided by the present invention, by controlling the reversal of the cooling fan and changing the direction of air flow, dust attached to the outside of the first filter device can be effectively removed, the permeability of the filter device can be maintained, the service life of the filter device can be extended, and the manual maintenance cost and maintenance frequency can be reduced.

[0024] In the control method of the wind turbine provided by the present invention, a comprehensive judgment is made through multiple parameters such as the operating status of the generator set and the air conditions near the first filter device, so as to accurately judge the blockage condition of the first filter device and automatically start the dust removal mode, thereby realizing intelligent control and improving the stability and reliability of the wind turbine operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, which will help to understand the objects and advantages of the present invention.

[0026] Figure 1 A perspective view of a specific embodiment of a filtering and dust removal system for a wind turbine according to the present invention;

[0027] Figure 2 A schematic structural diagram of a specific embodiment of a filtering and dust removal system for a wind turbine according to the present invention;

[0028] Figure 3 A system configuration diagram of a specific embodiment of a filtering and dust removal system for a wind turbine according to the present invention;

[0029] Figure 4 A control flow chart of a specific embodiment of the wind turbine of the present invention;

[0030] Figure 5 This is a flow chart of a method for determining filter blockage in a wind turbine according to the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0034] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] like Figure 1 、 Figure 2 The figure shows a specific embodiment of the filtering and dust removal system of the wind turbine provided by the present invention. On the one hand, the system is used to filter and cool the wind turbine when the wind turbine is working. On the other hand, it is used to remove dust from the filtering structure after the filtering structure (i.e., the first filtering device 13 below) is blocked and the wind turbine is shut down.

[0036] Specifically, the filtration and dust removal system primarily consists of a base 10, a cooling assembly 20, and a control unit. The wind turbine is a doubly-fed induction generator, with a base 10 that is roughly rectangular and hollow. The generator windings include stator windings 11 and rotor windings 12, with the rotor windings 12 mounted on a rotor shaft 17. Two sets of first filter devices 13 are mounted on the front and rear sides of the base 10, respectively. These first filter devices 13 utilize high-efficiency fiber filter material, effectively intercepting larger particles of dust, grit, and other impurities in the air, providing a preliminary protective barrier for the generator windings.

[0037] The cooling assembly 20 includes a cooling housing 21, a cooling fan 22, and a second filter device 23. The cooling housing 21 is mounted on the base 10. The cooling fan 22 and the second filter device 23 are mounted on the cooling housing 21. An air inlet and outlet 211 is provided on the side of the cooling housing 21 away from the base 10 for air intake and exhaust. The cooling fan 22 is a reversible axial flow fan capable of bidirectional operation.

[0038] The control unit is the core control component of the entire system. It can receive and process detection signals from various sensors in real time, and then control the generator set to switch between cooling mode and dust removal mode.

[0039] In the cooling mode, the control unit controls the cooling fan 22 to rotate forward. The external air is first filtered through the first filter device 13 on the front and rear sides of the machine base 10. After removing larger particles of impurities, it enters the interior of the machine base 10 to cool the generator windings (stator windings 11 and rotor windings 12), and then is discharged along the air inlet and outlet 211 of the cooling shell 21.

[0040] In the dust removal mode, the control unit controls the cooling fan 22 to reverse, and the external air enters the interior of the machine base 10 through the air inlet and outlet 211 of the cooling shell 21, and is then discharged along the first filter device 13 of the machine base 10. During this process, the airflow flows in the opposite direction, washing away the dust attached to the first filter device 13, thereby realizing self-cleaning of the filter device.

[0041] Specifically, in one optional embodiment, the cooling fan 22 includes a frequency conversion module, enabling high-precision frequency regulation. In dust removal mode, the control unit controls the cooling fan 22's frequency conversion module to periodically pulse output, generating a periodically varying airflow, enhancing the flushing of dust from the first filter 13 and improving dust removal effectiveness. This frequency conversion control method also reduces the fan's energy consumption, achieving energy-saving operation.

[0042] Specifically, the wind turbine is used in a wind turbine generator set with a variable pitch system. In dust removal mode, the control unit controls the variable pitch system to open the pitches at a negative angle, reversing the wind turbine's drive train. The cooling assembly 20 further includes two sets of coaxial fans 24 connected to the rotor shaft 17. The two sets of coaxial fans 24 are spaced apart on either side of the rotor winding 12 and rotate synchronously therewith. In cooling mode, the two sets of coaxial fans 24 generate airflow toward the rotor winding 12, enhancing air convection within the base 10 and further improving cooling. When the rotor shaft 17 rotates at high speed, the coaxial fans 24 also rotate at high speed, quickly removing heat generated by the generator windings and ensuring stable performance even under high-load conditions. In dust removal mode, the two sets of coaxial fans 24 generate reverse airflow away from the rotor winding 12. This turbulent airflow, combined with the airflow generated by the cooling fan 22, is blown out through the first filter device 13 to remove dust.

[0043] Specifically, the second filter device 23 is an electric louver-style filter device. The electric louver is composed of multiple shielding plates, each connected to the frame via a rotating shaft. A micromotor is mounted on the rotating shaft. The opening and closing of the louver is achieved by controlling the rotation angle of the micromotor. In cooling mode, the second filter device 23 is controlled to fully open the air inlet and outlet 211, allowing air to pass through the air inlet and outlet 211 unimpeded, ensuring maximum air flow and improving cooling efficiency. In dust removal mode, the second filter device 23 is controlled to partially block the air inlet and outlet 211. By adjusting the opening and closing angle of the louver, a certain amount of air resistance is created at the air inlet and outlet 211, increasing air flow rate and enhancing the dust removal effect of the first filter device 13. At the same time, it can also prevent dust from flowing along the cooling housing 21 into the machine base 10, thus performing a filtering function.

[0044] Specifically, the cooling shell 21 is installed on the upper side of the base 10, wherein a circular through hole is formed on the upper surface of the base 10, the cooling shell 21 comprises a mounting body 212 covering the upper side of the circular through hole and a wind duct 213 connected to the mounting body 212 and extending in the same direction as the rotor shaft 17, and the cooling fan 22 and the second filter device 23 are installed in the wind duct 213. More specifically, the second filter device 23 is located between the air inlet and outlet 211 of the cooling shell 21 and the cooling fan 22. The mounting body 212 is configured in a substantially cylindrical shape, and the center line of the substantially cylindrical mounting body 212 is perpendicular to the upper surface of the base 10, the wind duct 213 is configured in a cylindrical shape, the side surface of the mounting body 212 is connected to the cylindrical wind duct 213 through a square transition structure, and the wind duct 213 extends to an area away from the generator winding, so that the air can be effectively guided and concentrated, and the cooling fan 22 can uniformly draw and discharge air, thereby improving the air circulation efficiency. At the same time, the wind duct 213 can also protect the cooling fan 22 and the second filter device 23 to some extent, preventing external debris from entering and affecting the normal operation of the equipment.

[0045] Specifically, the dust concentration sensor adopts a laser scattering principle and can accurately detect the dust concentration in the air, and the air flow rate sensor adopts a thermal anemometer and can monitor the flow rate of the air in real time. The winding temperature sensor is arranged in the area close to the generator winding and adopts a thermocouple temperature sensor, which can quickly and accurately measure the temperature of the winding. The control unit controls the cooling fan 22 to switch between the cooling mode and the dust removal mode according to the detection signals of the genset power, the generator winding temperature rise, the winding temperature sensor, the dust concentration sensor and the air flow rate sensor. By combining the engine operating parameters with the air conditions near the first filter device 13 to determine whether the first filter device 13 is blocked, the false judgment and missed judgment can be avoided, and the stable operation of the wind turbine generator can be ensured. The specific determination method is described in the following control method.

[0046] Referring to Figure 4 , Figure 5 The present application also provides a specific implementation method of the control method of the wind turbine generator with the above-mentioned filtering and dust removal system, which comprises the following steps:

[0047] S1. Determine whether the first filter device 13 is blocked according to the operating state of the generator set and the air conditions near the first filter device 13.

[0048] Specifically, referring to Figure 5As shown, first determine whether the real-time power of the generator set is close to the full power state. The full power state refers to the maximum output power state that the generator set can achieve under rated operating conditions. If the real-time power T of the generator set is close to the full power T max The difference between them is less than or equal to the first threshold t (ie T max -T≤t), that is, the generator set is operating at close to full power. At this time, the first filter device 13 is likely to be blocked, and it is continued to be determined whether the generator winding temperature rise exceeds the second threshold value, wherein the generator winding temperature rise is obtained according to the detection values ​​of the winding temperature sensor and the ambient temperature sensor, and the generator winding temperature rise = (generator winding temperature value - ambient temperature value). If the generator winding temperature rise exceeds the second threshold value, for example, the generator winding temperature rise exceeds the warning limit of 95K, it is determined that the first filter device 13 is blocked; otherwise, it is determined that the first filter device 13 is not blocked.

[0049] If the difference between the real-time power and the full power of the unit is greater than the first threshold (T max -T>t), that is, the real-time power of the generator set is in a normal working state far less than the full power. At this time, the air condition in the area where the first filter device 13 is located is judged based on the detection signals of the dust concentration sensor and the air flow rate sensor near the first filter device 13. If the dust concentration exceeds the third threshold (for example, the third threshold is 100mg / m 3 ) and the air flow rate is lower than the fourth threshold value (for example, the fourth threshold value is 5m / s), it is determined that the first filter device 13 is blocked; otherwise, it is determined that the first filter device 13 is not blocked and the generator set maintains a normal working state.

[0050] By comprehensively evaluating multiple parameters, including the generator set's operating status (including real-time generator set power and generator winding temperature rise) and the air conditions near the first filter 13 (dust concentration and air flow rate), the system can accurately determine whether the first filter 13 is clogged. This multi-parameter evaluation method offers greater accuracy and reliability than single-parameter evaluation, avoiding misjudgments and missed detections and ensuring stable operation of the wind turbine.

[0051] S2. If it is determined according to the above step S1 that the first filter device 13 is not blocked, the generator set is kept in normal grid-connected operation, and the filtering and dust removal system is controlled to operate in cooling mode; specifically, the cooling fan 22 is controlled to rotate forward, and the shutters of the second filter device 23 are controlled to be in a fully open state, so that external air enters the interior of the base 10 through the first filter device 13, and the air flow is accelerated by the coaxial fan 24 arranged on the rotor shaft 17. The cooling gas flows through the stator winding 11 and the rotor winding 12 in turn, and is finally discharged along the air inlet and outlet 211 of the cooling shell 21, so as to quickly cool the generator set winding.

[0052] S3. If the first filter device 13 is blocked according to the above step S1, the dust removal mode is immediately started after the generator set is detected to be shut down. The dust removal mode includes controlling the generator set transmission chain and the cooling fan 22 to reverse, and controlling the shutter of the second filter device 23 to be in a semi-closed state. The specific control process is as follows: the generator set pitch system is controlled to open the pitch at a negative angle, so that the generator set transmission chain runs in the reverse direction (i.e., the direction opposite to the direction of the transmission chain when the generator set is in grid-connected working state), and the generator is controlled to operate near the synchronous speed, so that the generator set is in a safe state and prevents external turbulence from causing the unit to run away. At the same time, the frequency conversion module of the cooling fan 22 is controlled to cycle periodically n times in a pulse mode, and air enters the interior of the base 10 through the air inlet and outlet 211 of the cooling shell 21 to form turbulent wind and impact the first filter device 13 from the inside to the outside, increasing the air pressure blowing from the inside of the first filter device 13 to the outside, and blowing off the dust on its outer surface. Through this coordinated control method, efficient dust removal operation is achieved, ensuring that the first filter device 13 is cleaned without affecting the normal operation of the generator set.

[0053] More specifically, before the pulse mode is turned on, AC power with a rated voltage of 380V and an exchanged phase sequence (allowing the motor to rotate in the opposite direction) is input to the frequency conversion module through an electronic phase converter at a power frequency of 1Hz, and the cooling fan 22 starts slowly and keeps rotating in the opposite direction; then the frequency conversion module is controlled to make the power frequency reach 40Hz at a rate of 1Hz / s. At this time, the fan speed driven by the frequency conversion motor reaches 1200rpm, and the fan rotation speed has the basic speed wind speed to generate pulse wind.

[0054] The frequency converter module is controlled to activate pulse mode: the power frequency is increased from a first frequency f1 (e.g., 40 Hz) to a second frequency f2 (e.g., 60 Hz) at a first speed (e.g., 10 Hz / s) and maintained for a first duration t1 (e.g., 5 seconds). The cooling fan 22 is then driven to rapidly accelerate. The power frequency is then reduced from the second frequency f2 (e.g., 60 Hz) to the first frequency f1 (e.g., 40 Hz) at a second speed v2 (e.g., 1 Hz / s) and maintained for a second duration t2 (e.g., 2 seconds). After accelerating to high-speed mode, the cooling fan 22 is driven to slowly decelerate. This increases the amount of reverse airflow into the base 10, generating turbulence near the generator windings and impacting the filter surface from the inside out, blowing away attached dust. This pulse mode cycle is repeated 20 times as one dust removal operation.

[0055] After one dust removal operation, whether the first filter device 13 is blocked is determined by detecting the detection signals of the dust concentration sensor and the air flow rate sensor near the first filter device 13. If it is determined that the first filter device 13 is still in a blocked state, the above-mentioned dust removal operation is performed again until the detection signals of the dust concentration sensor and the air flow rate sensor meet the requirements.

[0056] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A filtration and dust removal system for a wind turbine, characterized in that: include: A machine base (10), wherein a generator winding is installed inside the machine base (10), and at least one set of first filtering devices (13) is provided on the machine base (10); A cooling assembly (20) comprises: a cooling shell (21) mounted on a machine base (10), and a cooling fan (22) and a second filter device (23) mounted in the cooling shell (21); an air inlet and outlet (211) is provided on a side of the cooling shell (21) away from the machine base (10); and the cooling fan (22) is a reversible axial flow fan; A control unit, wherein the control unit controls the filter dust removal system to switch between a cooling mode and a dust removal mode; In the cooling mode, the cooling fan (22) is controlled to rotate forward, and the external air enters the machine base (10) through the first filter device (13) and is discharged along the air inlet and outlet (211) of the cooling shell (21); In the dust removal mode, the cooling fan (22) is controlled to reverse, and the external air enters the interior of the machine base (10) through the air inlet and outlet (211) of the cooling shell (21) and is discharged along the first filter device (13) of the machine base (10).

2. A filtration and dust removal system for a wind turbine according to claim 1, characterized in that: The wind turbine generator is a double-fed induction generator. In the dust removal mode, the control unit controls the transmission chain of the wind turbine generator to reverse.

3. A filtration and dust removal system for a wind turbine according to claim 1, characterized in that: The generator winding comprises a stator winding (11) and a rotor winding (12), wherein the rotor winding (12) is mounted on a rotor shaft (17), and the cooling assembly (20) further comprises at least one group of coaxial fans (24) connected to the rotor shaft (17), wherein the coaxial fans (24) rotate synchronously with the rotor winding (12).

4. A filtration and dust removal system for a wind turbine according to claim 1, characterized in that: The cooling shell (21) includes an air guide tube (213) extending in the same direction as the rotor shaft (17), and the cooling fan (22) and the second filter device (23) are installed in the air guide tube (213).

5. A filtration and dust removal system for a wind turbine according to claim 1, characterized in that: The second filter device (23) is an electric shutter-type filter device. In cooling mode, the second filter device (23) is controlled to be in a state of fully opening the air inlet and outlet (211); in dust removal mode, the second filter device (23) is controlled to be in a state of at least partially blocking the air inlet and outlet (211).

6. A filtering and dust removal system for a wind turbine according to claim 1, characterized in that: A dust concentration sensor and / or an air flow rate sensor is provided in an area near the first filter device (13) in the base (10); and a winding temperature sensor is provided in an area near the generator winding in the base (10).

7. A filtration and dust removal system for a wind turbine according to claim 1, characterized in that: The cooling fan (22) has a frequency conversion module. In the dust removal mode, the control unit controls the frequency conversion module of the cooling fan (22) to output periodic pulses.

8. A method for controlling a wind turbine, characterized in that: include: determining whether the first filter device (13) is clogged based on the operating state of the generator set and the air flow condition near the first filter device (13); If the first filter device (13) is clogged, the dust removal mode is activated after the generator set is detected to be shut down. The dust removal mode includes controlling the generator set transmission chain and the cooling fan (22) to reverse, so that external air enters the interior of the base (10) through the air inlet and outlet (211) of the cooling shell (21) and is discharged along the first filter device (13) of the base (10).

9. A method for controlling a wind turbine according to claim 8, characterized in that: Determining whether the first filter device (13) is blocked according to the operating state of the generator set and the air flow condition near the first filter device (13) includes: If the difference between the real-time power and the full power of the generator set is less than or equal to a first threshold, determining whether the temperature rise of the generator winding exceeds a second threshold; if the temperature rise of the generator winding exceeds the second threshold, determining that the first filter device (13) is clogged; If the difference between the real-time power and the full power of the unit is greater than a first threshold, the dust concentration and the air flow rate in the area where the first filter device (13) is located are determined; if the dust concentration exceeds a third threshold and the air flow rate is lower than a fourth threshold, it is determined that the first filter device (13) is clogged.

10. The control method of a wind turbine according to claim 8, characterized in that: Controlling the reverse rotation of the generator set drive chain and the cooling fan (22) in the dust removal mode includes: Controlling the variable pitch system of the unit to open the propeller at a negative angle, and controlling the generator to operate near the synchronous speed; The frequency conversion module for controlling the cooling fan (22) cycles periodically n times in a pulse mode, wherein the pulse mode includes: increasing the power frequency from the first frequency f1 to the second frequency f2 at a first speed v1 and maintaining the power frequency for a first time duration t1; decreasing the power frequency from the second frequency f2 to the first frequency f1 at a second speed v2 and maintaining the power frequency for a second time duration t2; wherein v2 < v1, t1 > t2.

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