Variable pitch drive system, wind turbine generator, and variable pitch control method

Abstract

The application relates to a variable-pitch driving system, a wind turbine generator set and a variable-pitch control method. The variable-pitch driving system is used for driving a variable-pitch telescopic cylinder and a locking telescopic cylinder. The variable-pitch driving system comprises an energy station, a first driving module, a second driving module and a control valve group. The energy station is used for containing fluid and can provide power for fluid operation. The first driving module comprises a pair of first inlet pipes and a pair of first outlet pipes, and the first inlet pipes and the first outlet pipes are connected between the energy station and the variable-pitch telescopic cylinder. The second driving module comprises a pair of second inlet pipes and a pair of second outlet pipes, and the second inlet pipes and the second outlet pipes are connected between the energy station and the locking telescopic cylinder. The control valve group is arranged in the first driving module and the second driving module to control the communication or disconnection between at least one of the first driving module and the second driving module and the energy station. The embodiment of the application can realize the variable-pitch function under different working conditions and ensure the reliability.

Description

Technical Field

[0001] This application relates to the field of wind power generation technology, and in particular to a pitch drive system, a wind turbine generator set, and a pitch control method. Background Technology

[0002] With the rapid development of wind turbine technology, the capacity of wind turbines is constantly increasing, and the length of the turbine blades is also getting longer. Currently, the blade length of offshore turbines exceeds 90 meters and the weight exceeds 38 tons. For turbines with such long blades, pitch control is becoming increasingly difficult.

[0003] Furthermore, the blades require pitch control not only during service but also during turbine assembly or blade hoisting. This necessitates controlling the extension and retraction of the pitch cylinder and locking cylinder to achieve pitch control and locking. However, during turbine assembly or blade hoisting, issues such as power outages or inherent safety risks in the pitch system can make pitch control difficult and risky.

[0004] Therefore, a pitch drive system is urgently needed. Summary of the Invention

[0005] This application provides a pitch drive system, a wind turbine generator set, and a pitch control method. The pitch drive system can realize pitch control under different operating conditions and ensure reliability.

[0006] On one hand, according to an embodiment of this application, a pitch drive system is proposed for driving a pitch telescopic cylinder and a locking telescopic cylinder. The pitch drive system includes: an energy station for holding fluid and providing power for fluid movement; and a first drive module including a pair of first inlet pipes and first outlet pipes, both connected between the energy station and the pitch telescopic cylinder. The first inlet pipe guides the fluid from the energy station to one of the first rod chamber and the first rodless chamber of the pitch telescopic cylinder, and the first outlet pipe guides the fluid from the other of the first rod chamber and the first rodless chamber. The fluid is guided to the energy station; the second drive module includes a pair of second inlet pipes and second outlet pipes, both of which are connected between the energy station and the locking telescopic cylinder. The second inlet pipe guides the fluid from the energy station to one of the second rod-side chamber and the second rodless chamber of the locking telescopic cylinder, and the second outlet pipe guides the fluid from the other of the second rod-side chamber and the second rodless chamber to the energy station; a control valve group is disposed in the first drive module and the second drive module, and the control valve group can control the connection or disconnection between at least one of the first drive module and the second drive module and the energy station.

[0007] According to one aspect of the embodiments of this application, the control valve group includes a first valve and a second valve. The first valve is disposed on a first inlet pipe and can control the connection or disconnection of the first inlet pipe. The second valve is disposed on a second outlet pipe and can control the connection or disconnection of the second outlet pipe.

[0008] According to one aspect of the embodiments of this application, the second drive module includes a locking directional valve, which is disposed between the locking telescopic cylinder and the second valve. The second inlet pipe and the second outlet pipe are both connected to the locking directional valve. The locking directional valve can switch between a first state and a second state. In the first state, the second inlet pipe is connected to the second rod chamber and the second outlet pipe is connected to the second rodless chamber. In the second state, the second inlet pipe is connected to the second rodless chamber and the second outlet pipe is connected to the second rod chamber.

[0009] According to one aspect of the embodiments of this application, the control valve group further includes a third valve disposed on the second inlet pipe, and the second drive module further includes an accumulator connected to the second inlet pipe and located downstream of the third valve; the third valve is a one-way valve and is unidirectionally open from the energy station to the locking telescopic cylinder.

[0010] According to one aspect of the embodiments of this application, the first drive module further includes a pitch reversing valve, which is disposed between the pitch telescopic cylinder and the first valve. The first inlet pipe and the first outlet pipe are both connected to the pitch reversing valve. The pitch reversing valve can switch between a third state and a fourth state. In the third state, the first inlet pipe is connected to the first rod chamber and the first outlet pipe is connected to the first rodless chamber. In the fourth state, the first inlet pipe is connected to the first rodless chamber and the first outlet pipe is connected to the first rod chamber.

[0011] According to one aspect of the embodiments of this application, the first drive module further includes a bidirectional balance valve, which is disposed between the pitch telescopic cylinder and the pitch reversing valve, and the first inlet pipe and the first outlet pipe are both connected to the bidirectional balance valve.

[0012] According to one aspect of the embodiments of this application, the pitch drive system further includes a quick-connect fitting, wherein at least one of the first inlet pipe, the first outlet pipe, the second inlet pipe, and the second outlet pipe is connected to a port opposite to the power station via the quick-connect fitting.

[0013] According to one aspect of the embodiments of this application, the energy station includes a fluid inlet pipe and a fluid outlet pipe, the fluid inlet pipe being connected to a first inlet pipe and a second inlet pipe, and the fluid outlet pipe being connected to a first outlet pipe and a second outlet pipe; a first overflow valve is connected between the fluid outlet pipe and the fluid inlet pipe.

[0014] According to one aspect of the embodiments of this application, the first driving module further includes a first pressure relief branch and a second pressure relief branch. One end of the first pressure relief branch is connected to the first inlet pipe and the other end is connected to the fluid outlet pipe. One end of the second pressure relief branch is connected to the first outlet pipe and the other end is connected to the fluid outlet pipe. The control valve group further includes a fourth valve and a fifth valve. The fourth valve is disposed in the first pressure relief branch and is used to control the on / off state of the first pressure relief branch. The fifth valve is disposed in the second pressure relief branch and is used to control the on / off state of the second pressure relief branch.

[0015] According to one aspect of the embodiments of this application, the second drive module further includes a third pressure relief branch, one end of which is connected to the second inlet pipe and the other end of which is connected to the second outlet pipe; the control valve group further includes a sixth valve, which is disposed in the third pressure relief branch and used to control the on / off state of the third pressure relief branch.

[0016] On the other hand, according to an embodiment of this application, a wind turbine generator set is proposed, including: an impeller, including a hub and blades; a pitch system, including a pitch bearing, a pitch telescopic cylinder, and a locking telescopic cylinder, wherein one of the inner ring and the outer ring of the pitch bearing is connected to the hub and the other is connected to the blades, the pitch telescopic cylinder is used to drive the inner ring and the outer ring to rotate relative to each other, and the locking telescopic cylinder is used to lock the relative arrangement of the blades and the hub; as described above, in the pitch drive system, a first inlet pipe is connected to one of the first rod chamber and the first rodless chamber of the pitch telescopic cylinder, a first outlet pipe is connected to the other of the first rod chamber and the first rodless chamber of the pitch telescopic cylinder, a second inlet pipe is connected to one of the second rod chamber and the second rodless chamber of the locking telescopic cylinder, and a second outlet pipe is connected to the other of the second rod chamber and the second rodless chamber.

[0017] Furthermore, according to an embodiment of this application, a method for pitch control using the aforementioned pitch drive system is proposed, comprising: connecting a first inlet pipe to one of the first rod chamber and the first rodless chamber of the pitch telescopic cylinder, and connecting a first outlet pipe to the other of the first rod chamber and the first rodless chamber; simultaneously connecting a second inlet pipe to one of the second rod chamber and the second rodless chamber of the locking telescopic cylinder, and connecting a second outlet pipe to the other of the second rod chamber and the second rodless chamber; disconnecting the first drive module from the power station via a control valve group; driving fluid in the power station into the second rod chamber of the locking telescopic cylinder, causing the locking telescopic cylinder to retract and the blade to unlock from the hub; connecting the first drive module to the power station via the control valve group; driving fluid in the power station into the first rod chamber or the first rodless chamber of the pitch telescopic cylinder, causing the blade to rotate relative to the hub, thereby achieving pitch control of the blade.

[0018] The pitch drive system, wind turbine generator set, and pitch control method provided in this application embodiment include an energy station for holding fluid and driving it into a first drive module and a second drive module. A first inlet pipe and a first outlet pipe are paired between the energy station and the first drive module, and a second inlet pipe and a second outlet pipe are paired between the energy station and the second drive module. The fluid can enter the first drive module and the second drive module through the first inlet pipe and the second inlet pipe, respectively, to control the extension and retraction of the pitch telescopic cylinder and the locking telescopic cylinder, satisfying the pitch control requirements and the locking requirements after pitch control. By setting control valve groups on the first drive module and the second drive module, the control valve groups can be manipulated as needed to control the connection sequence between the first drive module and the second drive module and the energy station. For example, the second drive module can be connected to the energy station first, while the first drive module is disconnected from the energy station to unlock the pitch telescopic cylinder. Then, the first drive module can be connected to the energy station to achieve pitch control, ensuring the pitch control requirements, the unlocking before pitch control, and the locking requirements after pitch control, thereby improving the reliability of the pitch drive system. Attached Figure Description

[0019] The features, advantages, and technical effects of exemplary embodiments of this application will now be described with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the structure of a wind turbine generator set according to an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of the structure of a pitch drive system according to an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the structure of a pitch drive system according to another embodiment of this application;

[0023] Figure 4 This is a partial structural diagram of a pitch drive system according to an embodiment of this application;

[0024] Figure 5 This is a schematic flowchart illustrating a method for pitch control in a pitch drive system according to an embodiment of this application.

[0025] in:

[0026] 1-Energy station; 1a-Fluid inlet pipe; 1b-Fluid outlet pipe; 11-First overflow valve; 12-Containment box; 13-Drive pump;

[0027] 2-First drive module; 2a-First inlet pipe; 2b-First outlet pipe; 21-Pitch reversing valve; 22-Two-way balance valve; 221-First balance valve; 222-Second balance valve; 2c-First pressure relief branch; 2d-Second pressure relief branch;

[0028] 3-Second drive module; 3a-Second inlet pipe; 3b-Second outlet pipe; 31-Lock-in directional valve; 32-Accumulator; 3c-Third pressure relief branch;

[0029] 41-First valve; 42-Second valve; 43-Third valve; 43a-Check valve; 44-Fourth valve; 45-Fifth valve; 46-Sixth valve;

[0030] 5 - Quick Connector; S1 - First State; S2 - Second State; S3 - Third State; S4 - Fourth State;

[0031] 100 - Pitch telescopic cylinder; 101 - First rod chamber; 102 - First rodless chamber; 103 - First drive rod; 104 - First piston;

[0032] 200 - Locking telescopic cylinder; 201 - Second rod chamber; 202 - Second rodless chamber; 203 - Second drive rod; 204 - Second piston.

[0033] 300 - Tower; 400 - Nacelle; 410 - Generator; 500 - Impeller; 510 - Hub; 520 - Blade. Detailed Implementation

[0034] The features and exemplary embodiments of various aspects of this application will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a comprehensive understanding of this application. However, it will be apparent to those skilled in the art that this application can be implemented without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of this application by illustrating examples. In the accompanying drawings and the following description, at least some well-known structures and techniques are not shown to avoid unnecessarily obscuring the application; and, for clarity, the dimensions of some structures may be exaggerated. Furthermore, the features, structures, or characteristics described below can be combined in any suitable manner in one or more embodiments.

[0035] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the pitch drive system, wind turbine generator set, or pitch control method of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0036] To better understand this application, the following will be combined with... Figures 1 to 5The pitch drive system, wind turbine generator set, and pitch control method according to the embodiments of the application are described in detail below.

[0037] Please see Figure 1 , Figure 1 This is a schematic diagram of a wind turbine generator set according to one embodiment of this application. The embodiment provides a wind turbine generator set including a rotor 500, a pitch control system, and a pitch drive system. The wind turbine generator set also includes a tower 300, a nacelle 400, and a generator 410. The tower 300 is connected to the wind turbine foundation, the nacelle 400 is located at the top of the tower 300, and the generator 410 is located within the nacelle 400. In some examples, the generator 410 may be located outside the nacelle 400; in others, it may be located inside. The rotor 500 includes a hub 510 and multiple blades 520 connected to the hub 510. The rotor 500 is connected to the shaft of the generator 410 via its hub 510. When wind power acts on the blades 520, it drives the entire rotor 500 and the shaft of the generator 410 to rotate, converting wind energy into electrical energy.

[0038] The pitch system is located inside the hub 510 and includes a pitch bearing, a pitch telescopic cylinder 100, and a locking telescopic cylinder 200. One of the inner and outer rings of the pitch bearing is connected to the hub 510 and the other is connected to the blade 520. The pitch telescopic cylinder 100 is used to drive the inner and outer rings to rotate relative to each other, and the locking telescopic cylinder 200 is used to lock the relative arrangement of the blade 520 and the hub 510. The pitch system enables the blade 520 to perform pitch control operations during service.

[0039] With the rapid development of wind turbine technology, the requirements for wind turbines are becoming increasingly stringent. To improve efficiency, the 520 blade requires pitch control not only during service but also during turbine assembly or blade hoisting. However, during turbine assembly or blade hoisting, issues such as power outages or inherent safety risks in the pitch control system make pitch control difficult and risky.

[0040] To address the aforementioned shortcomings, this application provides a pitch drive system. This pitch drive system can be manufactured and sold as a standalone product, or it can be used with a wind turbine generator set as part of it. When used with a wind turbine generator set, the pitch drive system can be used in conjunction with the pitch telescopic cylinder 100 and the locking telescopic cylinder 200 of the wind turbine generator set.

[0041] Please see Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the structure of a pitch drive system according to an embodiment of this application. Figure 3This is a schematic diagram of the structure of a pitch drive system according to another embodiment of this application. The pitch drive system provided in this application is used to drive a pitch telescopic cylinder 100 and a locking telescopic cylinder 200. The pitch drive system includes an energy station 1, a first drive module 2, a second drive module 3, and a control valve group.

[0042] Energy station 1 is used to hold fluid and provide power for its operation. Optionally, the fluid in the pitch drive system can be in liquid, gas, or a mixture of both. Optionally, energy station 1 may include a container 12 for holding the fluid, and energy station 1 may also include a drive pump 13 or other power element to be connected to the container 12 and provide power for the fluid to circulate in the pitch drive system.

[0043] The pitch drive system provided in this application can be used to drive the pitch telescopic cylinder 100 and the locking telescopic cylinder 200. The pitch telescopic cylinder 100 is used to cause the blade 520 to perform pitch operation. The pitch telescopic cylinder 100 may include multiple pitch telescopic cylinders 100 to cause multiple blades 520 to perform pitch operation. It is understood that each pitch telescopic cylinder 100 may also consist of at least two pitch telescopic cylinders 100, with at least two pitch telescopic cylinders 100 acting together on one blade 520.

[0044] For example, such as Figure 2 The two pitch telescopic cylinders 100 shown each have a first rod chamber 101 and a first rodless chamber 102. Optionally, a first drive rod 103 is provided in the first rod chamber 101. The first drive rod 103 can be disposed on the piston rod in the pitch telescopic cylinder 100. Of course, the first drive rod 103 can also be directly connected to a first piston 104, which separates the first rod chamber 101 and the first rodless chamber 102.

[0045] For example, when it is necessary to retract the first drive rod 103 of the pitch telescopic cylinder 100, fluid can be supplied to the first rod chamber 101 and the fluid in the first rodless chamber 102 can be released. When it is necessary to extend the first drive rod 103 of the pitch telescopic cylinder 100, fluid can be supplied to the first rodless chamber 102 and the fluid in the first rod chamber 101 can be released.

[0046] The locking telescopic cylinder 200 is used to lock or unlock the movement of the blade 520. The locking telescopic cylinder 200 has a second rod chamber 201 and a second rodless chamber 202. Optionally, a second drive rod 203 is provided in the second rod chamber 201. The second drive rod 203 can be disposed on the piston rod in the locking telescopic cylinder 200. Of course, the second drive rod 203 can also be directly connected to the second piston 204, which separates the second rod chamber 201 and the second rodless chamber 202.

[0047] Optionally, the locking telescopic cylinder 200 is also provided with an elastic component. The elastic component can be disposed between the inner wall of the second rodless cavity 202 and the second piston 204. Of course, the elastic component can also be disposed in the second rod cavity 201.

[0048] For example, when the elastic member is disposed in the second rod chamber 201, when it is necessary to retract the second drive rod 203 of the locking telescopic cylinder 200, fluid can be released from the second rodless chamber 202, and when it is necessary to extend the second drive rod 203 of the pitch telescopic cylinder 100, fluid can be supplied to the second rod chamber 201.

[0049] The first drive module 2 includes a first inlet pipe 2a and a first outlet pipe 2b arranged in pairs. The first inlet pipe 2a and the first outlet pipe 2b are both connected between the power station 1 and the pitch telescopic cylinder 100. The first inlet pipe 2a guides the fluid of the power station 1 to one of the first rod chamber 101 and the first rodless chamber 102 of the pitch telescopic cylinder 100, and the first outlet pipe 2b guides the fluid of the other of the first rod chamber 101 and the first rodless chamber 102 to the power station 1.

[0050] For example, the first inlet pipe 2a is connected to the first rod chamber 101, so that the fluid in the container 12 of the energy station 1 is guided into the first rod chamber 101 through the first inlet pipe 2a under the drive of the drive pump 13. The first outlet pipe 2b is connected to the first rodless chamber 102, so that the fluid in the first rodless chamber 102 is released through the first outlet pipe 2b and flows back into the container 12 of the energy station 1. With the above settings, a stable fluid can be maintained in the pitch telescopic cylinder 100. That is to say, the energy station 1 provides fluid to the first rod chamber 101 and releases fluid from the first rodless chamber 102, ensuring the stable operation of the pitch telescopic cylinder 100. This enables the first drive module 2 to perform pitch operation, realize the pitch function of the pitch drive system, and control the blade 520 to perform pitch operation.

[0051] The second drive module 3 includes a second inlet pipe 3a and a second outlet pipe 3b arranged in pairs. The second inlet pipe 3a and the second outlet pipe 3b are both connected between the energy station 1 and the locking telescopic cylinder 200. The second inlet pipe 3a guides the fluid of the energy station 1 to one of the second rod chamber 201 and the second rodless chamber 202 of the locking telescopic cylinder 200, and the second outlet pipe 3b guides the fluid of the other of the second rod chamber 201 and the second rodless chamber 202 to the energy station 1.

[0052] For example, the second inlet pipe 3a is connected to the second rod chamber 201, so that the fluid in the container 12 of the energy station 1 is guided into the second rod chamber 201 through the second inlet pipe 3a under the drive of the drive pump 13. The second outlet pipe 3b is connected to the second rodless chamber 202, so that the fluid in the second rodless chamber 202 is released through the second outlet pipe 3b and flows back into the container 12 of the energy station 1. With the above settings, a stable fluid can be maintained in the locking telescopic cylinder 200. That is, the energy station 1 provides fluid to the second rod chamber 201 and releases fluid from the second rodless chamber 202, ensuring the stable operation of the pitch telescopic cylinder 100, causing the second drive rod 203 to retract, thereby causing the second drive module 3 to perform an unlocking operation to unlock the blade 520 so that it can move.

[0053] The control valve assembly is located in the first drive module 2 and the second drive module 3. The control valve assembly can control the connection or disconnection between at least one of the first drive module 2 and the second drive module 3 and the energy station 1.

[0054] Optionally, the control valve group controls the connection or disconnection between the first drive module 2 and the energy station 1, so as to control the first drive module 2 to turn on or off the pitch drive function.

[0055] Optionally, the control valve group controls the connection or disconnection between the second drive module 3 and the energy station 1, so as to control the second drive module 3 to open or close the pitch unlocking function.

[0056] Furthermore, by controlling the opening and closing sequence of the control valve groups on the first drive module 2 and the second drive module 3, for example, first opening the control valve group on the second drive module 3 to provide a stable fluid to the locking telescopic cylinder 200, thereby enabling the second drive module 3 to perform an unlocking operation to unlock the blade 520 and allow it to move. Then, opening the control valve group on the first drive module 2 to provide a stable fluid to the pitch telescopic cylinder 100, thereby enabling the first drive module 2 to perform a pitch operation, thus realizing the pitch function of the pitch drive system and controlling the blade 520 to perform pitch operation. Through this setting, the pitch drive system can not only realize the pitch function, but also improve safety and reliability.

[0057] Please continue reading. Figure 2 In some optional embodiments, the control valve assembly includes a first valve 41 and a second valve 42. The first valve 41 is disposed on the first inlet pipe 2a and can control the connection or disconnection of the first inlet pipe 2a. The second valve 42 is disposed on the second outlet pipe 3b and can control the connection or disconnection of the second outlet pipe 3b.

[0058] By setting a first valve 41 and a second valve 42 in the first inlet pipe 2a and the second outlet pipe 3b respectively, the connection or disconnection between the first drive module 2 and the second drive module 3 and the energy station 1 can be controlled independently. This allows the fluid of the energy station 1 to enter the pitch telescopic cylinder 100 and the locking telescopic cylinder 200 respectively, so that the fluids in the pitch telescopic cylinder 100 and the locking telescopic cylinder 200 will not affect each other, thus improving the reliability of the pitch drive system.

[0059] In some optional embodiments, the second drive module 3 includes a locking directional valve 31, which is disposed between the locking telescopic cylinder 200 and the second valve 42. The second inlet pipe 3a and the second outlet pipe 3b are both connected to the locking directional valve 31, which can switch between the first state S1 and the second state S2.

[0060] Optionally, the locking directional valve 31 is disposed between the locking telescopic cylinder 200 and the second valve 42. When the second valve 42 is opened, fluid passes through the locking directional valve 31 and enters the locking telescopic cylinder 200, thereby controlling the locking or unlocking of the locking telescopic cylinder 200.

[0061] The locking directional valve 31 can switch between the first state S1 and the second state S2 so that the locking telescopic cylinder 200 can perform an unlocking operation or a locking operation.

[0062] In the first state S1, the second inlet pipe 3a is connected to the second rod chamber 201, and the second outlet pipe 3b is connected to the second rodless chamber 202. In this state, the fluid of the energy station 1 enters the second rod chamber 201 of the locking telescopic cylinder 200 through the first inlet pipe 2a, and the second drive rod 203 retracts so that the fluid in the second rodless chamber 202 enters the energy station 1 through the second outlet pipe 3b, thereby causing the locking telescopic cylinder 200 to perform an unlocking operation.

[0063] In the second state S2, the second inlet pipe 3a is connected to the second rodless chamber 202, and the second outlet pipe 3b is connected to the second rod chamber 201. In this state, the fluid of the energy station 1 enters the second rodless chamber 202 of the locking telescopic cylinder 200 through the second inlet pipe 3a, and the second drive rod 203 extends so that the fluid in the second rod chamber 201 enters the energy station 1 through the second outlet pipe 3b, thereby causing the locking telescopic cylinder 200 to perform a locking operation.

[0064] Optionally, the locking directional valve 31 can be a solenoid valve or a manual valve.

[0065] During operation, the pitch drive system may experience abnormal phenomena such as fluid leakage or malfunction, resulting in a lack of stable fluid entering the locking telescopic cylinder 200. This could lead to the risk of the locking telescopic cylinder 200 automatically locking, alarming, or shutting down, affecting the normal operation of the pitch drive system and posing a safety hazard.

[0066] To address the aforementioned deficiencies, in some alternative embodiments, the control valve assembly further includes a third valve 43 disposed on the second inlet pipe 3a, and the second drive module 3 further includes an accumulator 32, which is connected to the second inlet pipe 3a and located downstream of the third valve 43.

[0067] Accumulator 32 can pre-store a certain amount of fluid to compensate for a certain amount of fluid leakage. By setting accumulator 32 in the second inlet pipe 3a, when the fluid entering the locking telescopic cylinder 200 is insufficient to control its unlocking operation, the fluid in accumulator 32 can be used as compensation to enter the locking telescopic cylinder 200, so that a stable amount of fluid enters the locking telescopic cylinder 200, ensuring the stable operation of the locking telescopic cylinder 200 and improving the reliability of the pitch drive system.

[0068] Optionally, the third valve 43 is a one-way valve 43a, with unidirectional flow from the energy station 1 to the locking telescopic cylinder 200. By setting the third valve 43 as a one-way valve 43a, fluid can only enter the locking telescopic cylinder 200 in one direction, ensuring that the locking telescopic cylinder 200 always performs an unlocking operation. Furthermore, the accumulator 32 is located downstream of the one-way valve 43a, preventing fluid in the accumulator 32 from flowing back to the energy station 1 through the one-way valve 43a. This ensures that fluid can enter the locking telescopic cylinder 200, thereby guaranteeing stable operation of the locking telescopic cylinder 200 and keeping it in the unlocked state. This prevents the locking telescopic cylinder 200 from automatically locking due to system pressure loss or other malfunctions, ensuring the safety and reliability of the pitch drive system.

[0069] In some optional embodiments, the first drive module 2 further includes a pitch reversing valve 21, which is disposed between the pitch telescopic cylinder 100 and the first valve 41. The first inlet pipe 2a and the first outlet pipe 2b are both connected to the pitch reversing valve 21, and the pitch reversing valve 21 can switch between the third state S3 and the fourth state S4.

[0070] Optionally, the pitch directional valve 21 can be a single manual directional valve; alternatively, it can be a single solenoid valve. The pitch directional valve 21 can be any type of solenoid valve, as long as it allows fluid to enter and exit the pitch telescopic cylinder 100. Optionally, the pitch directional valve 21 can also be an electrically operated directional valve.

[0071] In the third state S3, the pitch control valve 21 is controlled to connect the first inlet pipe 2a to the first rod chamber 101 and the first outlet pipe 2b to the first rodless chamber 102. In this state, the fluid of the energy station 1 enters the first rod chamber 101 of the pitch telescopic cylinder 100 through the first inlet pipe 2a, and the first drive rod 103 retracts so that the fluid in the first rodless chamber 102 enters the energy station 1 through the first outlet pipe 2b, thereby causing the pitch telescopic cylinder 100 to perform pitch operation, thus realizing the opening of the blade 520.

[0072] In the fourth state S4, the pitch control valve 21 is controlled to connect the first inlet pipe 2a to the first rodless chamber 102 and the first outlet pipe 2b to the first rod chamber 101. In this state, the fluid of the power station 1 enters the first rodless chamber 102 of the pitch telescopic cylinder 100 through the first inlet pipe 2a, and the first drive rod 103 extends so that the fluid in the first rod chamber 101 enters the power station 1 through the first outlet pipe 2b, thereby causing the pitch telescopic cylinder 100 to perform pitch operation, thereby achieving feathering of the blade 520.

[0073] Optionally, when the pitch telescopic cylinder 100 includes multiple pitch telescopic cylinders 100, it is only necessary to satisfy that multiple first drive rods 103 simultaneously perform extension or retraction movements.

[0074] In some optional embodiments, the first drive module 2 further includes a bidirectional balance valve 22, which is disposed between the pitch telescopic cylinder 100 and the pitch reversing valve 21, and the first inlet pipe 2a and the first outlet pipe 2b are both connected to the bidirectional balance valve 22.

[0075] By setting up a bidirectional balance valve 22, the drive rod of the pitch telescopic cylinder 100 is prevented from extending, retracting, or wobbling arbitrarily in the event of a power outage. This ensures the safety and reliability of the pitch drive system in achieving the pitch function, thereby enabling the blade 520 to operate stably during pitch control. Furthermore, the bidirectional balance valve 22 also controls the pitch telescopic cylinder 100 to maintain the blade 520 at a specific pitch angle during pitch control, facilitating maintenance or other operations, ensuring safety, and enhancing versatility.

[0076] Alternatively, the two-way balance valve 22 can also be a hydraulic balance valve.

[0077] Please see Figure 4 , Figure 4This is a partial structural diagram of a pitch drive system according to an embodiment of this application. In some optional embodiments, the bidirectional balance valve 22 may include a first balance valve 221 and a second balance valve 222. The first outlet A2 of the bidirectional balance valve 22 is connected to one of the first rod chamber 101 and the first rodless chamber 102, and the second outlet B2 is connected to the other of the first rod chamber 101 and the first rodless chamber 102. The first inlet A1 and the second inlet B1 of the bidirectional balance valve 22 may be connected to the power station 1, respectively. Optionally, the first inlet A1 and the second inlet B1 of the bidirectional balance valve 22 may be connected to the pitch directional valve 21, respectively.

[0078] Optionally, when it is necessary to retract the first drive rod 103 of the pitch telescopic cylinder 100, the first outlet A2 of the first balance valve 221 can be connected to the first rod chamber 101 to supply fluid to the first rod chamber 101, while the second outlet B2 of the second balance valve 222 is connected to the first rodless chamber 102 to release the fluid in the first rodless chamber 102. When it is necessary to extend the first drive rod 103 of the pitch telescopic cylinder 100, it is only necessary to change the connection relationship between the first balance valve 221 and the second balance valve 222 and the first rod chamber 101 and the first rodless chamber 102, which will not be elaborated further here.

[0079] Please continue reading. Figure 4 The pitch directional valve 21 can be a three-position four-way valve. Port A of the pitch directional valve 21 can be connected to one of the first inlet A1 and the second inlet B1 of the first balance valve 221. Port B of the pitch directional valve 21 can be connected to the other of the first inlet A1 and the second inlet B1 of the second balance valve 222. Port P of the pitch directional valve 21 is set on the fluid inlet pipe 1a and connected to the drive pump 13 of the energy station 1. Port T of the pitch directional valve 21 is set on the fluid outlet pipe 1b and connected to the housing 12 of the energy station 1, so as to control the flow of fluid between the energy station 1 and the pitch telescopic cylinder 100.

[0080] In order to achieve the hoisting of the blade 520 during the assembly of the unit or the hoisting of the blade 520, many pipelines are required to connect with the pitch telescopic cylinder 100 and the locking telescopic cylinder 200. The pipelines are numerous and the connections are complex, which not only results in low assembly efficiency, but also may lead to fluid leakage due to poor connection.

[0081] To address the aforementioned deficiencies, in some alternative embodiments, the pitch drive system further includes a quick-connect fitting 5, wherein at least one of the first inlet pipe 2a, the first outlet pipe 2b, the second inlet pipe 3a, and the second outlet pipe 3b is connected to a port opposite to the power station 1 via the quick-connect fitting 5.

[0082] For example, please continue reading Figure 3The first inlet pipe 2a and the first outlet pipe 2b are each provided with quick-connect fittings 5 ​​to connect to the first rod chamber 101 and the first rodless chamber 102 of the pitch telescopic cylinder 100, respectively. The second inlet pipe 3a and the second outlet pipe 3b are each provided with quick-connect fittings 5 ​​to connect to the second rod chamber 201 and the second rodless chamber 202 of the locking telescopic cylinder 200, respectively.

[0083] Optionally, the first inlet pipe 2a and the second inlet pipe 3a may also be provided with multiple quick-connect fittings 5. For example, the first inlet pipe 2a and the first outlet pipe 2b may be provided with quick-connect fittings 5 ​​to connect with the pitch reversing valve 21. After being connected with the pitch reversing valve 21, the first inlet pipe 2a and the first outlet pipe 2b may also be provided with quick-connect fittings 5 ​​to connect with the pitch telescopic cylinder 100.

[0084] By incorporating quick-connect fittings 5 ​​to connect the first inlet pipe 2a and the second outlet pipe 3b to the pitch telescopic cylinder 100, the second inlet pipe 3a and the second outlet pipe 3b to the locking telescopic cylinder 200, and the first inlet pipe 2a and the first outlet pipe 2b to the pitch reversing valve 21, on-site installation and disassembly are facilitated, improving work efficiency and making assembly more convenient. Furthermore, quick-connect fittings 5 ​​reduce fluid leakage during assembly, preventing environmental pollution.

[0085] In some alternative embodiments, the energy station 1 includes a fluid inlet pipe 1a and a fluid outlet pipe 1b, the fluid inlet pipe 1a being connected to a first inlet pipe 2a and a second inlet pipe 3a, and the fluid outlet pipe 1b being connected to a first outlet pipe 2b and a second outlet pipe 3b.

[0086] The fluid in energy station 1 flows out through fluid inlet pipe 1a and enters the first drive module 2 through the first inlet pipe 2a, and can also enter the second drive module 3 through the second inlet pipe 3a. The fluid in the first drive module 2 flows out through the first outlet pipe 2b and returns to energy station 1 through fluid outlet pipe 1b, and the fluid in the second drive module 3 flows out through the second outlet pipe 3b and returns to energy station 1 through fluid outlet pipe 1b.

[0087] Please continue reading. Figure 3 In some optional embodiments, a first relief valve 11 is connected between the fluid outlet pipe 1b and the fluid inlet pipe 1a to regulate the maximum pressure of the pitch drive system. When the fluid flowing out of the power station 1 from the fluid outlet pipe 1b exceeds the load of the pitch drive system, the excess fluid can flow back to the power station 1 through the first relief valve 11 from the fluid outlet pipe 1b to ensure the pressure of the pitch drive system is stable and its operation is stable.

[0088] Optionally, a first filter 14 may be installed on the fluid outlet pipe 1b to remove impurities that may be carried by the fluid entering the energy station 1, ensuring the effectiveness of the energy station 1. Optionally, the first filter 14 may be installed downstream of the first relief valve 11. It is understood that a second filter 15 may also be installed on the fluid inlet pipe 1a to remove impurities that may be carried by the fluid entering the pitch drive system, ensuring the safe operation of the pitch drive system. Optionally, the second filter 15 may be installed upstream of the control valve assembly.

[0089] After the wind turbine assembly or blade hoisting is completed, to avoid safety risks due to the remaining load on the pitch drive system during pipeline removal, please refer to the following: Figure 4 In some optional embodiments, the first drive module 2 further includes a first pressure relief branch 2c and a second pressure relief branch 2d. One end of the first pressure relief branch 2c is connected to the first inlet pipe 2a and the other end is connected to the fluid outlet pipe 1b. One end of the second pressure relief branch 2d is connected to the first outlet pipe 2b and the other end is connected to the fluid outlet pipe 1b. The control valve group further includes a fourth valve 44 and a fifth valve 45. The fourth valve 44 is disposed in the first pressure relief branch 2c and is used to control the on / off state of the first pressure relief branch 2c. The fifth valve 45 is disposed in the second pressure relief branch 2d and is used to control the on / off state of the second pressure relief branch 2d.

[0090] By controlling the opening of the fourth valve 44, the fluid in the pitch telescopic cylinder 100 can flow out through the first inlet pipe 2a, and then enter the first outlet pipe 2b through the first pressure relief branch 2c to flow back to the power station 1, thus returning the fluid in the pitch telescopic cylinder 100 to the power station 1. By controlling the opening of the fifth valve 45, the fluid in the pitch telescopic cylinder 100 can flow out through the first outlet pipe 2b, and then enter the first outlet pipe 2b through the second pressure relief branch 2d to flow back to the power station 1. Through this setting, all the fluid in the pitch telescopic cylinder 100 is discharged, thereby avoiding the risks caused by pressurized operation of the pitch drive system and improving the reliability of the system.

[0091] Please continue reading. Figure 3 In some optional embodiments, the second drive module 3 further includes a third pressure relief branch 3c, one end of which is connected to the second inlet pipe 3a and the other end of which is connected to the second outlet pipe 3b. The control valve group further includes a sixth valve 46, which is disposed in the third pressure relief branch 3c and used to control the on / off state of the third pressure relief branch 3c.

[0092] By controlling the opening of the sixth valve 46, the fluid in the locking telescopic cylinder 200 can flow out through the second inlet pipe 3a, and then enter the second outlet pipe 3b through the third pressure relief branch 3c to flow back to the power station 1, thus returning the fluid in the locking telescopic cylinder 200 to the power station 1. This arrangement ensures that all the fluid in the locking telescopic cylinder 200 is discharged, thereby avoiding the risks associated with pressurized operation of the pitch drive system and improving system reliability.

[0093] Optionally, the control valve assembly may further include a second relief valve 16, which is disposed between the second inlet pipe 3a and the second outlet pipe 3b and connected in parallel with the sixth valve 46 to regulate the maximum pressure of the pitch drive system. When the fluid flowing out of the energy station 1 from the second inlet pipe 3a exceeds the load of the pitch drive system, the excess fluid can flow back to the energy station 1 through the second outlet pipe 3b via the second relief valve 16 to ensure stable pressure in the pitch drive system and its stable operation.

[0094] Optionally, the inlet of the second relief valve 16 is connected to the outlet of the second valve 42, and the outlet of the second relief valve 16 can be connected to the inlet of the second filter 15.

[0095] This application also provides a wind turbine generator set, including a rotor 500, a pitch system, and a pitch drive system as described above.

[0096] The impeller 500 includes a hub 510 and blades 520. The pitch system includes a pitch bearing, a pitch telescopic cylinder 100, and a locking telescopic cylinder 200. One of the inner and outer rings of the pitch bearing is connected to the hub 510 and the other is connected to the blades 520. The pitch telescopic cylinder 100 is used to drive the inner and outer rings to rotate relative to each other, and the locking telescopic cylinder 200 is used to lock the relative arrangement of the blades 520 and the hub 510.

[0097] The first inlet pipe 2a of the pitch drive system is connected to one of the first rod chamber 101 and the first rodless chamber 102 of the pitch telescopic cylinder 100, and the first outlet pipe 2b is connected to the other of the first rod chamber 101 and the first rodless chamber 102 of the pitch telescopic cylinder 100. The second inlet pipe 3a is connected to one of the second rod chamber 201 and the second rodless chamber 202 of the locking telescopic cylinder 200, and the second outlet pipe 3b is connected to the other of the second rod chamber 201 and the second rodless chamber 202.

[0098] The pitch drive system controls the locking telescopic cylinder 200 to unlock the blade 520, enabling relative movement between it and the hub 510. The pitch drive system also controls the pitch telescopic cylinder 100 to drive the inner and outer rings of the pitch bearing to rotate relative to each other, thus changing the pitch of the blade 520. This allows the wind turbine generator set to achieve pitch control of the blade 520 even during assembly or hoisting, ensuring reliable operation.

[0099] This application also provides a method for pitch control using the above-described pitch drive system. Please refer to [link to relevant documentation]. Figure 5 The pitch control method includes:

[0100] S100: Connect the first inlet pipe 2a to one of the first rod chamber 101 and the first rodless chamber 102 of the pitch telescopic cylinder 100, and connect the first outlet pipe 2b to the other of the first rod chamber 101 and the first rodless chamber 102. At the same time, connect the second inlet pipe 3a to one of the second rod chamber 201 and the second rodless chamber 202 of the locking telescopic cylinder 200, and connect the second outlet pipe 3b to the other of the second rod chamber 201 and the second rodless chamber 202.

[0101] S200, the first drive module 2 is disconnected from the energy station 1 by controlling the valve group.

[0102] S300, the fluid in the drive energy station 1 enters the second rod chamber 201 of the locking telescopic cylinder 200, causing the locking telescopic cylinder 200 to retract and the blade 520 to unlock the hub 510.

[0103] S400, The first drive module 2 is connected to the energy station 1 through the control valve group.

[0104] S500, the fluid in the drive energy station 1 enters the first rod chamber 101 or the first rodless chamber 102 of the pitch telescopic cylinder 100, causing the blade 520 to rotate relative to the hub 510, thereby realizing the pitch of the blade 520.

[0105] Optionally, in step S100, the first inlet pipe 2a is connected to the first rod chamber 101 of the pitch telescopic cylinder 100, and the first outlet pipe 2b is connected to the first rodless chamber 102. At the same time, the second inlet pipe 3a is connected to the second rod chamber 201 of the locking telescopic cylinder 200, and the second outlet pipe 3b is connected to the second rodless chamber 202.

[0106] In step S200, the first drive module 2 is disconnected from the energy station 1 by controlling the valve group. Optionally, the first valve 41, the fourth valve 44, the fifth valve 45, and the sixth valve 46 are closed to disconnect the first drive module 2 from the energy station 1, preventing fluid from the energy station 1 from entering the first drive module 2.

[0107] In step S300, the second valve 42 is opened to allow fluid in the energy station 1 to enter the second rod chamber 201 of the locking telescopic cylinder 200, causing the locking telescopic cylinder 200 to retract and the blade 520 to unlock from the hub 510.

[0108] In step S400, the first drive module 2 is connected to the energy station 1 via a control valve group. Optionally, the first valve 41 is opened and the second valve 42 is closed to allow fluid in the energy station 1 to enter the first rod chamber 101 of the telescopic cylinder.

[0109] In step S500, the fluid in the drive energy station 1 enters the first rod chamber 101 or the first rodless chamber 102 of the pitch telescopic cylinder 100, causing the blade 520 to rotate relative to the hub 510, thereby realizing the pitch of the blade 520.

[0110] This application provides a method for pitch control using the aforementioned pitch drive system, which enables the blades 520 to perform pitch operations even when the turbine is unable to supply power or when there are safety risks inherent in the pitch system itself, making pitch operation difficult. Furthermore, this pitch control method ensures that pitch requirements, including unlocking before and locking after pitch control, are met, improving the reliability of the pitch control system and guaranteeing the normal and stable operation of the wind turbine generator. This makes the pitch control method effective and feasible.

[0111] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A variable pitch drive system for driving a variable pitch telescopic cylinder (100) and a locking telescopic cylinder (200), characterized in that, The variable pitch drive system comprises: An energy station (1) for containing fluid and capable of providing power for the fluid to run; A first drive module (2) comprising a pair of first inlet pipes (2a) and first outlet pipes (2b), the first inlet pipes (2a) and the first outlet pipes (2b) are connected between the energy station (1) and the variable pitch telescopic cylinder (100), the first inlet pipes (2a) guide the fluid in the energy station (1) to one of the first rod cavity (101) and the first rodless cavity (102) of the variable pitch telescopic cylinder (100), and the first outlet pipes (2b) guide the fluid in the other one of the first rod cavity (101) and the first rodless cavity (102) to the energy station (1); A second drive module (3) comprising a pair of second inlet pipes (3a) and second outlet pipes (3b), the second inlet pipes (3a) and the second outlet pipes (3b) are connected between the energy station (1) and the locking telescopic cylinder (200), the second inlet pipes (3a) guide the fluid in the energy station (1) to one of the second rod cavity (201) and the second rodless cavity (202) of the locking telescopic cylinder (200), and the second outlet pipes (3b) guide the fluid in the other one of the second rod cavity (201) and the second rodless cavity (202) to the energy station (1); A control valve group is arranged in the first drive module (2) and the second drive module (3), and the control valve group can control the communication or disconnection between at least one of the first drive module (2) and the second drive module (3) and the energy station (1); The second drive module (3) comprises a locking reversing valve (31) arranged between the locking telescopic cylinder (200) and the energy station (1), the second inlet pipes (3a) and the second outlet pipes (3b) are connected with the locking reversing valve (31), and the locking reversing valve (31) can be switched between a first state (S1) and a second state (S2); in the first state (S1), the second inlet pipes (3a) are in communication with the second rod cavity (201), and the second outlet pipes (3b) are in communication with the second rodless cavity (202); in the second state (S2), the second inlet pipes (3a) are in communication with the second rodless cavity (202), and the second outlet pipes (3b) are in communication with the second rod cavity (201).

2. The variable pitch drive system of claim 1, wherein, The control valve group comprises a first valve (41) and a second valve (42), the first valve (41) is arranged on the first inlet pipe (2a), and the first valve (41) can control the communication or disconnection of the first inlet pipe (2a); The second valve (42) is arranged on the second outlet pipe (3b), and the second valve (42) can control the communication or disconnection of the second outlet pipe (3b).

3. The variable pitch drive system of claim 2, wherein, The locking reversing valve (31) is arranged between the locking telescopic cylinder (200) and the second valve (42).

4. The variable pitch drive system of claim 2, wherein, The control valve group further comprises a third valve (43) arranged at the second inlet pipe (3a), and the second drive module (3) further comprises an accumulator (32) connected with the second inlet pipe (3a) and located downstream of the third valve (43). The third valve (43) is a one-way valve (43a) and is unidirectionally conducted from the energy station (1) to the locking telescopic cylinder (200).

5. The variable pitch drive system of claim 2, wherein, The first drive module (2) further comprises a pitch reversing valve (21) arranged between the pitch telescopic cylinder (100) and the first valve (41), and the first inlet pipe (2a) and the first outlet pipe (2b) are connected with the pitch reversing valve (21), and the pitch reversing valve (21) can be switched between a third state (S3) and a fourth state (S4). In the third state (S3), the first inlet pipe (2a) is in communication with the first rod cavity (101), and the first outlet pipe (2b) is in communication with the first rodless cavity (102). In the fourth state (S4), the first inlet pipe (2a) is in communication with the first rodless cavity (102), and the first outlet pipe (2b) is in communication with the first rod cavity (101).

6. The variable pitch drive system of claim 5, wherein, The first drive module (2) further comprises a bidirectional balance valve (22) arranged between the pitch telescopic cylinder (100) and the pitch reversing valve (21), and the first inlet pipe (2a) and the first outlet pipe (2b) are connected with the bidirectional balance valve (22).

7. The variable pitch drive system of any one of claims 1 to 6, wherein, The pitch drive system further comprises a quick connector (5), and at least one of the first inlet pipe (2a), the first outlet pipe (2b), the second inlet pipe (3a) and the second outlet pipe (3b) is connected with the quick connector (5) away from the energy station (1).

8. The variable pitch drive system of any one of claims 1 to 6, wherein, The energy station (1) comprises a fluid inlet pipe (1a) and a fluid outlet pipe (1b), the fluid inlet pipe (1a) is connected with the first inlet pipe (2a) and the second inlet pipe (3a), and the fluid outlet pipe (1b) is connected with the first outlet pipe (2b) and the second outlet pipe (3b). A first overflow valve (11) is connected between the fluid outlet pipe (1b) and the fluid inlet pipe (1a).

9. The variable pitch drive system of claim 8, wherein, The first drive module (2) further comprises a first pressure relief branch (2c) and a second pressure relief branch (2d), one end of the first pressure relief branch (2c) is in communication with the first inlet pipe (2a) and the other end is in communication with the fluid outlet pipe (1b), and one end of the second pressure relief branch (2d) is in communication with the first outlet pipe (2b) and the other end is in communication with the fluid outlet pipe (1b). The control valve group further comprises a fourth valve (44) and a fifth valve (45), the fourth valve (44) is arranged at the first pressure relief branch (2c) and is used for controlling the on-off of the first pressure relief branch (2c), and the fifth valve (45) is arranged at the second pressure relief branch (2d) and is used for controlling the on-off of the second pressure relief branch (2d).

10. The variable pitch drive system of any one of claims 1 to 6, wherein, The second drive module (3) further comprises a third pressure relief branch (3c), one end of the third pressure relief branch (3c) is connected with the second inlet pipe (3a) and the other end is connected with the second outlet pipe (3b); The control valve group further comprises a sixth valve (46), which is arranged in the third pressure relief branch (3c) and is used to control the opening and closing of the third pressure relief branch (3c).

11. A wind power unit, characterized in that Comprise: A blade wheel (500) comprising a hub (510) and a blade (520); A variable pitch system comprising a variable pitch bearing, a variable pitch telescopic cylinder (100) and a locking telescopic cylinder (200), one of the inner ring and the outer ring of the variable pitch bearing is connected with the hub (510) and the other is connected with the blade (520), the variable pitch telescopic cylinder (100) is used to drive the relative rotation of the inner ring and the outer ring, and the locking telescopic cylinder (200) is used to lock the relative arrangement of the blade (520) and the hub (510); The variable pitch driving system according to any one of claims 1 to 10, the first inlet pipe (2a) is connected with one of the first rod cavity (101) and the first rodless cavity (102) of the variable pitch telescopic cylinder (100), the first outlet pipe (2b) is connected with the other of the first rod cavity (101) and the first rodless cavity (102) of the variable pitch telescopic cylinder (100), the second inlet pipe (3a) is connected with one of the second rod cavity (201) and the second rodless cavity (202) of the locking telescopic cylinder (200), and the second outlet pipe (3b) is connected with the other of the second rod cavity (201) and the second rodless cavity (202).

12. A method of pitch control using the pitch drive system of any one of claims 1 to 10, characterized in that Comprise: The first inlet pipe (2a) is connected with one of the first rod cavity (101) and the first rodless cavity (102) of the variable pitch telescopic cylinder (100), and the first outlet pipe (2b) is connected with the other of the first rod cavity (101) and the first rodless cavity (102), while the second inlet pipe (3a) is connected with one of the second rod cavity (201) and the second rodless cavity (202) of the locking telescopic cylinder (200), and the second outlet pipe (3b) is connected with the other of the second rod cavity (201) and the second rodless cavity (202); The first drive module (2) is disconnected from the energy station (1) by the control valve group; The fluid in the energy station (1) is driven into the second rod cavity (201) of the locking telescopic cylinder (200), so that the locking telescopic cylinder (200) is contracted, and the blade (520) is unlocked from the hub (510); The first drive module (2) is connected with the energy station (1) by the control valve group; The fluid in the energy station (1) is driven into the first rod cavity (101) or the first rodless cavity (102) of the variable pitch telescopic cylinder (100), so that the blade (520) rotates relative to the hub (510), realizing the variable pitch of the blade (520).

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