Hydraulic yaw system and wind turbine generator

Abstract

This invention provides a hydraulic yaw system and a wind turbine generator set. The hydraulic yaw system includes a hydraulic tank, a hydraulic drive unit, a drive oil circuit module, a replenishment drive unit, and a replenishment oil circuit module. The hydraulic drive unit drives the nacelle to rotate. The drive oil circuit module connects the hydraulic tank and the hydraulic drive unit, selectively supplying hydraulic oil from the tank to the hydraulic drive unit. The replenishment drive unit is selectively connected to the hydraulic drive unit. The replenishment oil circuit module connects the replenishment drive unit, the hydraulic drive unit, and the hydraulic tank. When the wind turbine generator set has a power supply, the hydraulic drive unit and the replenishment drive unit are disconnected, forming a hydraulic oil circuit passing through the drive oil circuit module and the hydraulic drive unit. When the wind turbine generator set has no power supply, the hydraulic drive unit and the replenishment drive unit are rotatably connected, forming a hydraulic oil circuit passing through the replenishment oil circuit module and the replenishment drive unit, achieving passive yaw of the nacelle without power.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and in particular to a hydraulic yaw system and a wind turbine generator set. Background Technology

[0002] Existing wind turbines, under normal operating conditions and with a power supply, generally employ an electric yaw system to achieve precise wind alignment. The working principle of this electric yaw system is that the yaw motor operates under electric drive, which in turn drives the gearbox, ultimately causing the nacelle to rotate around the tower's axis. This ensures that the wind turbine rotor is always accurately aligned with the wind direction, thereby guaranteeing the wind turbine's efficient and stable capture of wind energy and its power generation function.

[0003] However, when a wind turbine experiences a sudden malfunction, grid outage, or other reasons that render it without power, the electric yaw system will fail to operate normally. At this time, the yaw motor stops working due to the loss of power, and the nacelle is mechanically locked at a fixed angle. However, the external wind direction is constantly changing. This inevitably leads to a deviation between the fixed angle of the nacelle and the actual wind direction, meaning there is an error in the yaw system's windward angle.

[0004] This deviation in wind angle can trigger a series of serious problems. On the one hand, it will subject the wind turbine to a greater load, increasing the stress on various components and accelerating wear and aging over long-term operation. On the other hand, it will lead to increased vibration of the turbine, affecting its stability and reliability. If this deviation continues to worsen and is not effectively controlled, it may even lead to the risk of the turbine collapsing. Summary of the Invention

[0005] The purpose of this invention is to provide a hydraulic yaw system and a wind turbine generator set, providing a hydraulic yaw system that can yaw without power supply, so as to solve the technical problem that existing wind turbine generator sets cannot yaw when there is no power supply.

[0006] According to a first aspect of the present invention, a hydraulic yaw system is provided, wherein the hydraulic yaw system is used in the nacelle of a wind turbine generator set, wherein the hydraulic yaw system includes: a hydraulic oil tank, a hydraulic drive unit, a drive oil circuit module, and a replenishment oil circuit module, wherein the hydraulic drive unit is used to drive the nacelle to rotate; the drive oil circuit module connects the hydraulic oil tank and the hydraulic drive unit, and is used to selectively supply hydraulic oil from the hydraulic oil tank to the hydraulic drive unit; the replenishment oil drive unit is selectively connected to the hydraulic drive unit; the replenishment oil circuit module connects the replenishment oil drive unit, the hydraulic drive unit, and the hydraulic oil tank; wherein, when the wind turbine generator set has a power supply, the hydraulic drive unit is disconnected from the replenishment oil drive unit to form a hydraulic oil circuit passing through the drive oil circuit module and the hydraulic drive unit; when the wind turbine generator set has no power supply, the hydraulic drive unit is rotatably connected to the replenishment oil drive unit to form a hydraulic oil circuit passing through the replenishment oil circuit module and the replenishment oil drive unit.

[0007] In some embodiments, the fluid replenishment circuit module includes a flow regulation unit disposed between the output end of the hydraulic drive unit and the hydraulic oil tank; wherein, the flow regulation unit can reduce the flow rate of hydraulic oil flowing through the hydraulic drive unit in the next moment if the rotational speed of the hydraulic drive unit at the current moment is greater than a first preset threshold; or, the flow regulation unit can increase the flow rate of hydraulic oil flowing through the hydraulic drive unit in the next moment if the rotational speed of the hydraulic drive unit at the current moment is not greater than the first preset threshold.

[0008] In some embodiments, the flow regulating unit includes a hydraulic throttle valve disposed between the output end of the oil replenishment drive unit and the hydraulic oil tank.

[0009] In some embodiments, the flow regulation unit further includes a first valve body, which is disposed adjacent to the hydraulic throttle valve between the output end of the oil replenishment drive unit and the hydraulic oil tank. When the wind turbine generator set has no power supply, the first valve body is in an open state, and the valve opening of the hydraulic throttle valve decreases in response to the rotation speed of the hydraulic drive unit being greater than a first preset threshold and the rotation speed of the hydraulic drive unit increasing.

[0010] In some embodiments, the oil replenishment drive unit includes a rotating part and a connecting structure, wherein the rotating part is connected to the hydraulic oil tank and the oil replenishment circuit module; the connecting structure can selectively connect the rotating part and the hydraulic drive unit; wherein, when the connecting structure and the hydraulic drive unit are connected, the hydraulic drive unit can drive the rotating part to rotate, thereby causing the hydraulic drive unit to be rotatably connected to the rotating part to drive the rotating part to supply oil to the oil replenishment circuit module; when the connecting structure and the hydraulic drive unit are disconnected, the hydraulic drive unit is disconnected from the rotating part to disconnect the oil supply from the rotating part to the oil replenishment circuit module.

[0011] In some embodiments, the connection structure is a clutch, which can disconnect the rotating part and the hydraulic drive part when the wind turbine has a power supply, and can connect the rotating part and the hydraulic drive part when the wind turbine has no power; and / or, the rotating part is an oil replenishment pump.

[0012] In some embodiments, the hydraulic drive unit is at least one hydraulic motor.

[0013] In some embodiments, the drive hydraulic circuit module includes: a pumping device, a directional regulating valve, and a flow rate regulating unit. The directional regulating valve connects the pumping device and the hydraulic drive unit, and also connects the hydraulic oil tank and the hydraulic drive unit. The flow rate regulating unit is disposed between the directional regulating valve and the hydraulic oil tank. The hydraulic yaw system further includes a control unit, which is communicatively connected to the hydraulic drive unit and the flow rate regulating unit. The control unit controls the flow rate regulating unit to reduce the rotational speed of the hydraulic drive unit in response to the rotational speed of the hydraulic drive unit exceeding a speed threshold.

[0014] In some embodiments, the flow rate regulating unit is a proportional throttle valve, which is disposed between the outlet of the directional regulating valve and the hydraulic oil tank.

[0015] In some embodiments, the control unit controls the opening degree of the proportional throttle valve to be not less than 90% in response to the rotational speed of the hydraulic drive unit not exceeding a preset rotational speed threshold.

[0016] In some embodiments, the hydraulic yaw system further includes: a slip control oil circuit connected to the inlet and outlet of the hydraulic drive unit. When the hydraulic drive unit is disconnected from both the replenishment oil circuit module and the drive oil circuit module, in response to the oil pressure of the slip control oil circuit exceeding a first pressure threshold, hydraulic oil can flow through the slip control oil circuit through the inlet and outlet of the hydraulic drive unit to cause the hydraulic drive unit to rotate, thereby driving the engine room to slip.

[0017] In some embodiments, the slip control oil circuit includes a second valve body and a first relief valve, which are connected in series between the inlet and outlet of the hydraulic drive unit. The pressure setting value of the second valve body is equal to the first pressure threshold. When the pressure difference between the inlet and outlet of the hydraulic drive unit exceeds the pressure setting value of the first relief valve, the second valve body opens and the first relief valve overflows to circulate oil to the hydraulic drive unit.

[0018] In some embodiments, the hydraulic yaw system further includes an oil pressure protection unit, which is connected in parallel with the slip control oil circuit and operates separately from the slip control oil circuit, so that the pressure difference between the inlet and outlet of the hydraulic drive unit does not exceed a second pressure threshold, wherein the second pressure threshold is greater than the first pressure threshold.

[0019] In some embodiments, the hydraulic protection unit includes a second relief valve, the set pressure value of which is equal to the second pressure threshold, and overflows in response to the pressure difference between the inlet and outlet of the hydraulic drive unit exceeding the set pressure value of the second relief valve.

[0020] In some embodiments, the hydraulic yaw system further includes a hydraulic braking unit and a brake circuit module. The hydraulic braking unit is disposed on one side of the hydraulic drive unit. The brake circuit module connects the hydraulic oil tank and the hydraulic braking unit, and is capable of supplying oil to the hydraulic braking unit to disconnect the hydraulic drive unit from the hydraulic braking unit; and is capable of cutting off the oil supply to the hydraulic braking unit to connect the hydraulic drive unit to the hydraulic braking unit.

[0021] In some embodiments, the brake hydraulic circuit module includes a control valve, a backup power supply, and an accumulator. The control valve is used to disconnect or connect the hydraulic drive unit and the hydraulic brake unit. The backup power supply is connected to the control valve. The accumulator is connected between the control valve and the hydraulic oil tank, and the accumulator can supply oil to the hydraulic brake unit through the control valve. In the event that the wind turbine generator set has no power supply, the backup power supply can supply power to the control valve to open the control valve, thereby supplying oil to the hydraulic drive unit through the accumulator, thus disconnecting the hydraulic drive unit and the hydraulic brake unit.

[0022] According to a second aspect of this application, a wind turbine generator set is provided, wherein the wind turbine generator set includes: a tower and a nacelle, the nacelle being mounted on the tower and driven by a hydraulic yaw system according to the above description to achieve yaw.

[0023] According to the hydraulic yaw system and wind turbine generator of this application, when the wind turbine generator has a power supply (powered), the hydraulic drive unit and the oil replenishment drive unit are disconnected to form a hydraulic oil circuit through the drive oil circuit module and the hydraulic drive unit, causing the hydraulic drive unit to actively drive the nacelle to yaw. Furthermore, at this time, the hydraulic drive unit and the oil replenishment drive unit are disconnected, ensuring that the oil replenishment drive unit and the oil replenishment circuit module do not affect the operation of the hydraulic drive unit. When the wind turbine generator has no power supply (e.g., due to a power failure), the hydraulic yaw system switches to a mode where the hydraulic drive unit and the oil replenishment drive unit are rotatably connected. In this mode, when the hydraulic drive unit of the hydraulic yaw system is rotated by an external force (e.g., wind force), it drives the oil replenishment drive unit to rotate, thereby driving the hydraulic oil in the hydraulic oil tank to circulate and supply oil to the hydraulic drive unit through the oil replenishment circuit module. This enables the hydraulic drive unit to drive the nacelle to yaw passively when there is no power, solving a series of problems caused by the wind turbine generator unit in the event of a power outage. For example, by moving the yaw without power, the nacelle can be smoothly and controllably rotated slowly to the leeward position (safe position), instead of violently oscillating back and forth or getting stuck. This can reduce the risk of the wind turbine tower collapsing due to heavy loads, unit vibrations, etc., when there is no power supply. Attached Figure Description

[0024] The above and other aspects, features, and advantages of the present invention will become clearer and more readily understood from the following detailed description of exemplary embodiments taken in conjunction with the accompanying drawings, in which: Figure 1 This is a schematic diagram of the connection between the hydraulic drive unit and components such as the tower in the hydraulic yaw system provided according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a hydraulic yaw system provided according to an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the disconnection between the hydraulic drive unit and the hydraulic braking unit of the hydraulic yaw system provided according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the hydraulic yaw system provided according to an embodiment of the present invention during electrically active yaw. Figure 5 This is a schematic diagram of the hydraulic yaw system provided in the embodiment of the present invention during yaw overspeed. Figure 6 This is a schematic diagram of the hydraulic yaw system provided in the embodiment of the present invention during yaw slip. Figure 7 This is a schematic diagram of the hydraulic yaw system provided in the embodiment of the present invention during passive yaw without electricity.

[0025] Tag Name 10. Hydraulic oil tank; 20. Hydraulic drive unit; 30. Hydraulic braking unit; 40. Drive oil circuit module; 41. Directional adjustment valve; 42. First passage; 43. Second passage; 44. Flow rate adjustment unit; 45. Third passage; 46. Fourth passage; 50. Braking oil circuit module; 51. Control valve; 52. Fifth passage; 53. Sixth passage; 54. Accumulator; 60. Fluid replenishment oil circuit module; 61. Fluid replenishment inlet; 62. Fluid replenishment outlet; 63. Flow rate adjustment unit; 631. First valve body; 632. Hydraulic throttle valve; 64. Heat dissipation unit; 641. First connecting pipe; 642. Drive motor; 643. Fan; 644. Radiator; 70. Fluid replenishment drive unit; 71. Rotating part; 72. Connecting structure; 80. Control unit; P. First working port; T. Second working port; A. Third working port; B. Fourth working port; 100. Pumping device; 110. Slip control oil circuit; 111. Second connecting pipeline; 112. Second valve body; 113. First relief valve; 120. Oil pressure protection unit; 121. Third connecting pipeline; 122. Second relief valve; 130. Loading valve; 141. First node; 142. Second node; 143. Third node; 200, Tower; 210, Yaw Gear Ring; 220, Reducer; 230, Reduction Gear; 300, Base. Detailed Implementation

[0026] The following detailed descriptions are provided to aid the reader in gaining a full understanding of the methods and apparatus described herein. However, various changes, modifications, and equivalents of the methods and apparatus described herein will become apparent upon understanding the disclosure of this invention. For example, the order of operations described herein is merely illustrative and is not limited to those orders set forth herein, but may be changed as will become clear upon understanding the disclosure of this invention, except for operations that must occur in a specific order. Furthermore, for clarity and conciseness, descriptions of features known in the art may be omitted.

[0027] The features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided only to illustrate some of the many possible ways in which the methods, apparatus and / or systems described herein may be implemented, many of which will become clear upon understanding the disclosure of the invention.

[0028] As used herein, the term “and / or” includes any one of the associated listed items and any combination of any two or more.

[0029] Although terms such as “first,” “second,” and “third” may be used herein to describe various components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts should not be limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Thus, without departing from the teaching of the examples described herein, the first component, first assembly, first region, first layer, or first part referred to as the first component, first assembly, first region, first layer, or first part may also be referred to as the second component, second assembly, second region, second layer, or second part.

[0030] The terminology used herein is for describing various examples only and is not intended to limit the invention. Unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. The terms “comprising,” “including,” and “having” indicate the presence of the described features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof. The term “a plurality” represents any number of two or more.

[0031] The directional terms "upper," "lower," "inner," and "outer" used in this invention are all based on the reference position of the hydraulic yaw system in normal operating condition. This definition method will help ensure that readers or users can clearly understand the relative positional relationships of the various components and functions, and should not be construed as limiting the invention.

[0032] Unless otherwise defined, all terms used herein, including technical and scientific terms, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains upon understanding the invention. Unless expressly defined herein, terms such as those defined in a general dictionary shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field and in this invention, and shall not be interpreted in an idealized or overly formalistic manner.

[0033] Furthermore, in the description of the examples, detailed descriptions of well-known related components or functions will be omitted when it is believed that such detailed descriptions would lead to a vague interpretation of the invention.

[0034] The following will combine Figures 1 to 7 The present application will now introduce a hydraulic yaw system provided by an embodiment of this application.

[0035] Figure 1 This is a schematic diagram of the connection between the hydraulic drive unit and components such as the tower in the hydraulic yaw system provided according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a hydraulic yaw system provided according to an embodiment of the present invention; Figure 3This is a schematic diagram illustrating the disconnection between the hydraulic drive unit and the hydraulic braking unit of the hydraulic yaw system provided according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the hydraulic yaw system provided according to an embodiment of the present invention during electrically active yaw. Figure 5 This is a schematic diagram of the hydraulic yaw system provided in the embodiment of the present invention during yaw overspeed. Figure 6 This is a schematic diagram of the hydraulic yaw system provided in the embodiment of the present invention during yaw slip. Figure 7 This is a schematic diagram of the hydraulic yaw system provided in the embodiment of the present invention during passive yaw without electricity.

[0036] This application provides a hydraulic yaw system for use in the nacelle of a wind turbine generator. Wherein, as Figures 1 to 7 As shown, the hydraulic yaw system includes a hydraulic oil tank 10, a hydraulic drive unit 20, a drive oil circuit module 40, a replenishment drive unit 70, and a replenishment oil circuit module 60. The hydraulic drive unit 20 drives the nacelle to rotate. The drive oil circuit module 40 connects the hydraulic oil tank 10 and the hydraulic drive unit 20, selectively supplying hydraulic oil from the hydraulic oil tank 10 to the hydraulic drive unit 20. The replenishment drive unit 70 is selectively connected to the hydraulic drive unit 20. The replenishment oil circuit module 60 connects the replenishment drive unit 70, the hydraulic drive unit 20, and the hydraulic oil tank 10. When the wind turbine generator has power, the hydraulic drive unit 20 and the replenishment drive unit 70 are disconnected, forming a hydraulic oil circuit passing through the drive oil circuit module 40 and the hydraulic drive unit 20. When the wind turbine generator has no power, the hydraulic drive unit 20 and the replenishment drive unit 70 are rotatably connected, forming a hydraulic oil circuit passing through the replenishment oil circuit module 60 and the replenishment drive unit 70.

[0037] According to the hydraulic yaw system of this application, when the wind turbine generator is powered (energized), the hydraulic drive unit 20 is disconnected from the oil replenishment drive unit 70 to form a hydraulic oil circuit passing through the drive oil circuit module 40 and the hydraulic drive unit 20, causing the hydraulic drive unit 20 to actively drive the nacelle to yaw. Furthermore, at this time, the hydraulic drive unit 20 is disconnected from the oil replenishment drive unit 70, ensuring that the oil replenishment drive unit 70 and the oil replenishment circuit module 60 do not affect the operation of the hydraulic drive unit 20. When the wind turbine is without power (e.g., due to a power failure), the hydraulic yaw system switches to a mode where the hydraulic drive unit 20 and the oil replenishment drive unit 70 are rotatably connected. In this mode, when the hydraulic drive unit 20 of the hydraulic yaw system rotates under external force (e.g., wind), it drives the oil replenishment drive unit 70 to rotate, thereby circulating the hydraulic oil in the hydraulic oil tank 10 to supply oil to the hydraulic drive unit 20 via the oil replenishment circuit module 60. This enables the hydraulic drive unit 20 to drive the nacelle to passively yaw without power, resolving a series of problems caused by the wind turbine in the absence of power. For example, by moving the yaw without power, the nacelle can smoothly and controllably rotate slowly to the leeward position (safe position), instead of violently oscillating back and forth or jamming. This reduces the risk of the wind turbine tower collapsing due to heavy loads, unit vibration, etc., in the absence of power.

[0038] In this application, when the wind turbine generator has no power supply (e.g., due to a power failure), when the wind speed is high enough, the wind can move the nacelle of the wind turbine generator, thereby driving the hydraulic drive unit 20 to rotate with the wind. It can be understood that when the wind turbine generator has no power supply, wind energy serves as the power source for starting the hydraulic fluid supply module 60. After the hydraulic drive unit 20 receives power from the wind, it drives the hydraulic fluid supply module 70 to rotate, thereby driving the hydraulic oil in the hydraulic oil tank 10 to circulate and supply oil to the hydraulic drive unit 20 via the hydraulic fluid supply module 60. In this way, in the event of a power failure, the wind turbine generator can be kept stable in a leeward position, ensuring the safe operation of the wind turbine generator.

[0039] According to this application, the hydraulic oil tank 10 is used at least to store hydraulic oil and provide hydraulic oil for the entire hydraulic yaw system. The hydraulic drive unit 20 serves as a drive mechanism (drive component) for driving the nacelle yaw. As an example, the hydraulic drive unit 20 can be a hydraulic motor, which can actively drive the nacelle yaw based on yaw demand when there is a power supply, and can be driven by wind when there is no power supply, driving the oil replenishment drive unit 70 to work as a pump to draw hydraulic oil from the hydraulic oil tank 10.

[0040] According to this application, when the wind turbine generator set has no power supply, the oil replenishment module 60 forms an independent circulating oil circuit to circulate oil to the hydraulic drive unit 20, so as to ensure that the hydraulic drive unit 20 can achieve oil-driven operation in the absence of power supply, thereby achieving the purpose of passive yaw without power.

[0041] During passive yaw without electricity, the wind load varies. The rotational speed of the hydraulic drive unit 20 is closely related to the flow rate of the hydraulic oil. Under high wind load, the rotational speed of the hydraulic drive unit 20 is also high. In this case, reducing the flow rate of the hydraulic oil can reduce the rotational speed of the hydraulic drive unit 20, thus preventing it from running out of control due to excessive wind load and ensuring that the hydraulic drive unit 20 operates within a safe and reasonable speed range. Under low wind load, the rotational speed of the hydraulic drive unit 20 increases, ensuring passive yaw without electricity even with low wind load, thereby further improving the operational safety of the wind turbine generator set.

[0042] In some embodiments of this application, the fluid replenishment circuit module 60 includes a flow regulation unit 63 (throttling unit or damping unit). The flow regulation unit 63 is disposed between the output end of the hydraulic drive unit 20 and the hydraulic oil tank 10. The flow regulation unit 63 can reduce the flow rate of hydraulic oil flowing through the hydraulic drive unit 20 at the next moment if the rotational speed of the hydraulic drive unit 20 at the current moment is greater than a first preset threshold. It can be understood that the flow regulation unit 63 can reduce the flow rate of hydraulic oil in the fluid replenishment circuit module 60, thereby reducing the rotational speed of the hydraulic drive unit 20. Simultaneously, a controllable throttling effect (back pressure) is generated in the oil circuit, which is equivalent to reverse control of the flow rate of hydraulic oil entering the input end of the hydraulic drive unit 20, thereby directly reducing the movement speed of the hydraulic drive unit 20 at the next moment, and realizing the regulation of the movement speed of the hydraulic drive unit 20.

[0043] In other embodiments of this application, the flow regulating unit 63 can also increase the flow rate of hydraulic oil in the hydraulic drive unit 20 at the next moment, provided that the rotational speed of the hydraulic drive unit 20 at the current moment is not greater than (less than or equal to) a first preset threshold. In this case, the flow regulating unit 63 can increase the flow rate of hydraulic oil in the hydraulic drive unit 20 at the next moment, providing the necessary back pressure to ensure passive yaw at low speeds, thereby further improving the smoothness and safety of the hydraulic yaw system. Simultaneously, in a preferred embodiment, the flow regulating unit 63 can maintain its maximum opening during low-speed operation to ensure the possibility of low-speed yaw.

[0044] In these embodiments, by providing a flow regulating unit 63 between the output end of the hydraulic drive unit 20 and the hydraulic oil tank 10, the rotational speed of the hydraulic drive unit 20 can be reduced when the hydraulic yaw system performs passive yaw without power, thus avoiding excessive speed and enabling passive yaw without power at low speeds, thereby ensuring the safety and reliability of the cabin under passive yaw without power.

[0045] According to this application, the flow regulation unit 63 is used to regulate the flow rate of the replenishment oil outlet 62 of the replenishment oil circuit module 60, thereby linking the oil supply from the replenishment oil circuit module 60 to the hydraulic drive unit 20 with the rotational speed of the hydraulic drive unit 20, so as to realize the speed regulation of the hydraulic drive unit 20 during passive yaw, ensuring that the nacelle can rotate smoothly and slowly to the leeward position, rather than violently oscillating or rotating rapidly under the impact of wind, avoiding huge impact on the tower and foundation structure, and the risk of tower collapse.

[0046] In this application, the flow regulation unit 63 includes a hydraulically controlled throttle valve 632, which is disposed between the output end of the oil replenishment drive unit 70 (e.g., an oil replenishment pump) and the hydraulic oil tank 10. In this application, the hydraulically controlled throttle valve 632 can be a pure hydraulically controlled throttle valve, whose valve can be adjusted entirely by hydraulic force, thereby changing the flow rate of the oil replenishment outlet of the oil replenishment circuit module 60. Simultaneously, it ensures that the pressure (back pressure) of the oil replenishment outlet of the oil replenishment circuit module 60 is higher than atmospheric pressure, thus providing a damping effect and enabling the hydraulic drive unit 20 to operate smoothly. The entire process is hydraulically driven and hydraulically controlled, therefore requiring no external power intervention, and thus adaptable to situations where there is no power supply.

[0047] In some embodiments, the flow regulation unit 63 further includes a first valve body 631, which is disposed adjacent to the hydraulic throttle valve 632 between the output end of the oil replenishment drive unit 70 and the hydraulic oil tank 10. When the wind turbine generator set has no power supply, the first valve body 631 is in the open state, and the valve opening of the hydraulic throttle valve 632 decreases in response to the increase in the rotational speed of the hydraulic drive unit 20 when it exceeds a first preset threshold. In this way, damage to the wind turbine generator set caused by excessive rotational speed of the hydraulic drive unit 20 when there is no power yaw can be avoided. The first valve body 631 can be a single solenoid valve, such as a two-position two-way solenoid valve, or it can be a valve group module. The structure of the first valve body 631 is not specifically limited.

[0048] As a specific example, refer to Figure 7The fluid replenishment circuit module 60 further includes at least two replenishment inlets 61 and at least two replenishment outlets 62. The replenishment inlets 61 are connected between the inlets of the replenishment drive unit 70 and the hydraulic drive unit 20, and the replenishment outlets 62 are connected between the outlet of the hydraulic drive unit 20 and the hydraulic oil tank 10. A hydraulically controlled throttle valve 632 and a first valve body 631 are respectively disposed on the replenishment outlet 62 located between the output end of the hydraulic drive unit 20 and the hydraulic oil tank 10. In some embodiments, the fluid replenishment circuit module 60 further includes a heat dissipation unit 64, which is connected to the replenishment outlet 62 located between the flow regulating unit 63 and the hydraulic oil tank 10, for dissipating heat from the hydraulic oil flowing through the fluid replenishment circuit module 60. As a specific example, the heat dissipation unit 64 includes a drive motor 642, a fan 643, and a radiator 644. The drive motor 642 is connected to the oil replenishment outlet 62 and can rotate when the oil pressure inside the oil replenishment outlet 62 is greater than a preset value. The fan 643 is connected to the drive motor 642 and the radiator 644 is connected to the oil replenishment outlet 62. When there is oil pressure inside the oil replenishment outlet 62, the drive motor 642 can rotate under the drive of the oil pressure to drive the fan 643 to blow air onto the radiator 644, thereby cooling the hydraulic oil flowing through the oil replenishment circuit module 60.

[0049] In some embodiments, the oil replenishment drive unit 70 includes a rotating part 71 and a connecting structure 72, wherein the rotating part 71 is connected to the hydraulic oil tank 10 and the replenishment oil circuit module 60; the connecting structure 72 can selectively connect the rotating part 71 and the hydraulic drive unit 20; wherein, when the connecting structure 72 and the hydraulic drive unit 20 are connected, the hydraulic drive unit 20 can drive the rotating part 71 to rotate, thereby making the hydraulic drive unit 20 and the rotating part 71 rotatably connected, so as to drive the rotating part 71 to draw oil from the hydraulic oil tank 10 and supply oil to the replenishment oil circuit module 60. The hydraulic oil enters the oil inlet of the hydraulic drive unit 20, and after passing through the hydraulic drive unit 20, it enters the flow regulation unit 63. At this time, the flow regulation unit 63 will generate damping based on the current rotation speed of the hydraulic drive unit 20 being greater than a first preset threshold, so as to reduce the flow rate of the hydraulic oil flowing through the hydraulic drive unit 20 at the next moment, thereby ensuring that the hydraulic yaw system operates at low speed in the absence of electric yaw. When the connecting structure 72 and the hydraulic drive unit 20 are disconnected, the hydraulic drive unit 20 is disconnected from the rotating unit 71, thereby cutting off the oil supply from the rotating unit 71 to the replenishing oil circuit module 60.

[0050] In these embodiments, by providing the rotating part 71 and the connecting structure 72, the hydraulic drive part 20 and the rotating part 71 can be selectively connected to achieve the switching of corresponding working conditions when there is a power supply and when there is no power supply, so that the yaw system can perform corresponding actions according to its own needs.

[0051] As a specific example, the connection structure 72 is a clutch. The clutch can disconnect the rotating part 71 and the hydraulic drive part 20 when the wind turbine generator has a power supply, and can connect the rotating part 71 and the hydraulic drive part 20 when the wind turbine generator has no power supply. The clutch can realize the switching mode of energized separation and de-energized engagement. Once there is no power supply (for example, the main power supply is lost), the clutch will automatically reset by means of internal springs and other mechanisms, rotating the hydraulic drive part 20 and the rotating part 71 to drive the rotating part 71 to supply oil to the fluid replenishment module 60, so as to achieve yaw without power. When there is a power supply, the clutch will disconnect the connection between the hydraulic drive part 20 and the rotating part 71, and switch the drive oil circuit module 40 to supply oil to the hydraulic drive part 20, so as to achieve active yaw with power.

[0052] More specifically, the clutch can be an electromagnet clutch or a centrifugal clutch. Taking an electromagnet clutch as an example, when the wind turbine generator has a power supply, the electromagnet coil of the electromagnet clutch is energized, generating a magnetic field that attracts the clutch, disengaging it and breaking the connection between the rotating part and the hydraulic drive part. When the wind turbine generator has no power supply, the electromagnet coil of the electromagnet clutch demagnetizes, and the magnetic field disappears. At this time, under the action of the return spring, the clutch can connect the rotating part 71 (oil pump) to the hydraulic drive part 20 (such as a hydraulic motor), providing power transmission for yaw in the event of power failure. In these embodiments, no manual intervention or electrical signal control is required; the clutch's mechanical design (such as the return spring when the power is off) alone can achieve rapid response to oil circuit switching between power supply and power failure conditions, and it has high reliability.

[0053] As a specific example, the rotating part 71 is a replenishing oil pump. The replenishing oil pump can rotate with the hydraulic drive part 20 (such as a hydraulic motor). The power obtained by the replenishing oil pump will be used to drive the hydraulic oil in the hydraulic oil tank 10 into the replenishing oil circuit module 60, so as to pave the way for the circulation oil supply of the hydraulic drive part 20, so that the yaw system can have yaw function in the absence of power supply, to ensure the safety of the wind turbine generator in the absence of power supply, and reduce the risk of the wind turbine generator tower collapsing due to large load, unit vibration and other reasons in the absence of power supply.

[0054] In some embodiments, the hydraulic drive unit 20 is at least one hydraulic motor. When the wind turbine has no power supply and strong winds can cause the nacelle to rotate, the hydraulic drive unit 20 will rotate. Simultaneously, by engaging the oil replenishment drive unit 70 via a clutch, the hydraulic drive unit will also drive the oil replenishment drive unit 70 to operate. (Refer to...) Figure 7The rotation of the oil replenishment drive unit 70 causes hydraulic oil in the hydraulic oil tank 10 to be delivered to the inlet of the hydraulic drive unit 20 through the oil replenishment inlet 61, providing a continuous and sufficient supply of oil to the hydraulic drive unit 20. Additionally, the hydraulic oil discharged from the outlet of the hydraulic drive unit 20 returns smoothly to the hydraulic oil tank 10 through the oil replenishment outlet 62, thus forming a closed-loop circuit. This closed-loop circuit provides controllable damping for the yaw motion of the engine room in the absence of power, preventing the hydraulic drive unit 20 from idling and ensuring that the yaw system yaws passively in the absence of power.

[0055] In some embodiments, a third relief valve is provided between the outlet of the rotating part 71 and the inlet of the hydraulic drive part 20, and the third relief valve is equipped with a set relief pressure. (Refer to...) Figure 6 The third relief valve is located on the oil replenishment inlet 61. According to these embodiments, when the hydraulic yaw system is in use, the hydraulic oil entering the hydraulic drive unit 20 is ensured to always be lower than the set pressure of the third relief valve, under the restriction of the third relief valve. This ensures that the hydraulic drive unit 20 yaws slowly and stably even without power supply.

[0056] According to this application, when the wind turbine generator has a power supply, the hydraulic drive unit 20 is disconnected from the oil replenishment drive unit 70. The drive oil circuit module 40 acts as the main oil circuit and supplies high-pressure oil to the hydraulic drive unit 20 based on control commands, driving it to actively yaw. That is, when the wind turbine generator has a power supply, a hydraulic oil circuit can be formed through the drive oil circuit module 40 and the hydraulic drive unit 20, causing the hydraulic drive unit 20 to actively drive the nacelle to yaw. Here, it should be noted that when the drive oil circuit module 40 is powered, it acts as the main oil circuit, supplying high-pressure oil to the hydraulic drive unit 20 according to control commands, driving it to actively yaw. The aforementioned oil replenishment drive unit 70 is only rotated by the hydraulic drive unit 20 when the wind turbine generator has no power supply, acting as an oil replenishment pump to establish oil pressure and oil circulation for the passive yaw oil circuit (oil replenishment module 60).

[0057] In this application, the directional control valve 41 has the function of adjusting direction, and can adjust the oil supply direction of the hydraulic drive unit 20, thereby adjusting the rotation direction of the hydraulic drive unit 20 to adapt to the bidirectional rotation requirements of yaw. In addition, the directional control valve 41 has an adjustable valve opening, and the flow rate of hydraulic oil in the hydraulic drive unit 20 can be adjusted by adjusting the valve opening of the directional control valve 41 to meet the driving force requirements of the hydraulic drive unit 20 when actively driving the engine room to yaw.

[0058] The inventors also discovered that during active yaw operations, there may be issues affecting the safe and stable operation of the system. Specifically, when the wind load is excessive and the direction of the external force F1 is the same as the direction of the driving force F2, the thrust generated by the wind on the nacelle may increase abnormally. This increased thrust can make the yaw speed difficult to control, or even cause it to become uncontrollable, resulting in a significant acceleration trend in the nacelle. Furthermore, the rated speed of the hydraulic drive unit 20 is determined by the flow rate provided by the pumping device 100, and the flow rate that the hydraulic pump can provide has an upper limit and cannot be increased indefinitely. The increased thrust may cause the speed of the hydraulic drive unit 20 to exceed the safety limit, resulting in a speed exceeding the rated speed and affecting the lifespan of the hydraulic drive unit 20.

[0059] To better control and regulate the hydraulic yaw system, in some embodiments, the directional control valve 41 is configured as a proportional directional valve, which can be used to adjust the proportion and direction of hydraulic oil flow. However, the adjustment of the proportional directional valve is synchronous at both the inlet and outlet. For example, when the valve opening of the proportional directional valve is reduced, the opening size of the first working port P → the third working port A and the fourth working port B → the second working port T is simultaneously reduced. From this perspective, reducing the valve opening of the proportional directional valve will, on the one hand, increase the resistance at the right port of the hydraulic drive unit 20, and on the other hand, further reduce the oil supply at the left inlet of the hydraulic drive unit 20. When the speed of the hydraulic drive unit 20 exceeds the rated speed, the above adjustment method may result in a severe shortage of oil supply to the left side of the hydraulic drive unit 20, which may lead to cavitation in the hydraulic drive unit 20 and affect its performance.

[0060] Therefore, to facilitate control and prevent the hydraulic drive unit 20 from sucking in air, in a preferred embodiment, the drive oil circuit module 40 includes a pumping device 100, a directional adjustment valve 41, and a flow rate adjustment unit 44. The directional adjustment valve 41 connects the pumping device 100 and the hydraulic drive unit 20, forming an oil inlet path for the hydraulic drive unit 20, and also connects the hydraulic oil tank 10 and the hydraulic drive unit 20, forming a return path for the hydraulic drive unit 20. The flow rate adjustment unit 44 is disposed between the directional adjustment valve 41 and the hydraulic oil tank 10, specifically, between the outlet of the directional adjustment valve 41 and the hydraulic oil tank 10. The hydraulic yaw system also includes a control unit, which is communicatively connected to the hydraulic drive unit 20 and the flow rate adjustment unit 44. The control unit controls the flow rate adjustment unit 44 to reduce the rotational speed of the hydraulic drive unit 20 in response to the hydraulic drive unit 20's rotational speed exceeding a speed threshold.

[0061] In these embodiments, when the wind turbine is powered, the hydraulic yaw system can achieve active yaw by means of oil supply from the drive oil circuit module 40. Furthermore, the control unit can continuously monitor the actual rotational speed of the hydraulic drive unit 20 (e.g., a hydraulic motor) and compare the actual speed with a preset speed threshold, where the preset speed threshold is the rated speed of the hydraulic drive unit 20. If it is determined that the hydraulic drive unit 20 is in a high-speed state (high-load state), the control unit will issue a control command to the flow rate regulation unit 44 to reduce the rotational speed of the hydraulic drive unit 20 without causing damage to the hydraulic drive unit 20.

[0062] In some embodiments, the directional control valve 41 is a reversing valve with only a reversing function, and the flow rate regulating unit 44 is a proportional throttle valve. The directional control valve 41 is used to switch the yaw direction, and the flow rate regulating unit 44 is used to control the flow rate during overspeed. It can also be understood that adjusting the opening of the flow rate regulating unit 44 can increase the resistance at the outlet of the hydraulic drive unit 20, thereby achieving the effect of regulating the speed. At the same time, the oil supply at the inlet of the hydraulic drive unit 20 is sufficient, which can prevent the hydraulic drive unit 20 from running dry due to insufficient oil supply, thereby improving the service life of the hydraulic drive unit 20. As a specific example, the proportional throttle valve is set between the outlet of the directional control valve 41 and the hydraulic oil tank 10, and the flow rate regulating unit 44 is set between the outlet of the directional control valve 41 and the hydraulic oil tank 10. That is, the flow rate regulating unit 44 is installed on the return oil line of the hydraulic drive unit 20 (hydraulic motor). When the speed of the hydraulic drive unit 20 exceeds the rated speed, the control unit can reduce the valve opening of the flow rate regulating unit 44 located between the outlet of the directional regulating valve 41 and the hydraulic oil tank 10. This increases the resistance of the hydraulic oil flowing back to the hydraulic oil tank 10 from the drive oil circuit module 40 without affecting the inlet flow of the hydraulic drive unit 20, thus preventing the hydraulic drive unit 20 from idling. At the same time, a pressure higher than atmospheric pressure (i.e., back pressure) is formed in the return oil chamber, creating a controllable damping effect that effectively suppresses the excessive rotation speed of the hydraulic drive unit 20, thereby smoothly reducing its speed to a stable range and achieving overspeed control during electric yaw.

[0063] It should be noted that the solution of combining the directional control valve 41 with the proportional throttle valve is less expensive than the proportional valve directional valve. Furthermore, when yaw is overspeeding, it only throttles the return oil circuit, providing resistance to reduce speed and avoiding throttling on the inlet side, which would exacerbate the suction of the hydraulic drive unit 20.

[0064] In some embodiments, the control unit 80 controls the opening of the proportional throttle valve to be no less than 90% in response to the rotational speed of the hydraulic drive unit 20 not exceeding a preset speed threshold. Preferably, the control unit 80 controls the opening of the proportional throttle valve to be 100% in response to the rotational speed of the hydraulic drive unit 20 not exceeding the preset speed threshold. A 100% valve opening means that the return oil flow path is fully open, and the flow resistance is minimal. This ensures that the hydraulic oil flows smoothly back to the hydraulic oil tank and avoids unnecessary back pressure in the return oil path. This ensures that the hydraulic drive unit 20 can operate at the optimal speed without overspeeding, thereby improving the overall response speed and working efficiency of the yaw system.

[0065] Specifically, the directional control valve 41 is a reversing valve, which only has a reversing function and does not have the function of adjusting the flow ratio. Specifically, the reversing valve includes a first working port P, a second working port T, a third working port A, and a fourth working port B. The third working port A is connected to the inlet of the hydraulic drive unit 20, and the fourth working port B is connected to the outlet of the hydraulic drive unit 20. The drive oil circuit module 40 also includes a first passage 42 and a second passage 43. The first passage 42 connects the hydraulic oil tank 10 to the first working port P; the second passage 43 connects the second working port T to the hydraulic oil tank 10. The hydraulic yaw system also includes a pumping device 100, installed on the first passage 42, which can pump hydraulic oil from the hydraulic oil tank 10 to the drive oil circuit module 40. The control unit 80 is communicatively connected to the reversing valve, and the control unit 80 can control the first working port P and the third working port A to be open, and the second working port T and the fourth working port B to be open; or, the first working port P and the fourth working port B to be open, and the second working port T and the third working port A to be open. As a specific example, the flow rate regulating unit 44 is disposed on the second passage 43 and is communicatively connected to the control unit 80. When the control unit 80 controls the flow rate regulating unit 44 to reduce the speed of the hydraulic drive unit 20 in response to the speed exceeding the speed threshold, the flow rate regulating unit 44 can reduce the flow rate of the hydraulic oil in the second passage 43 based on the increment of the speed of the hydraulic drive unit 20 at the current moment, thereby reducing the speed of the hydraulic drive unit 20 at the next moment.

[0066] In existing yaw systems, yaw action is typically initiated when sensors detect a deviation between the nacelle's angle and the wind direction. Once the yaw reaches the designated position, a brake is used to fix the system in place. However, this method results in significant stress on the tower. Specifically, under high wind loads, the powerful wind load is directly transmitted to the tower via the gear ring, creating a huge impact and affecting the structural safety of the wind turbine. In these situations, if the force generated by the nacelle is T1, then the force transmitted to the tower is also T1.

[0067] According to this application, the hydraulic yaw system further includes a slip control oil circuit 110, which is connected to the inlet and outlet (e.g., oil inlet and oil outlet) of the hydraulic drive unit 20. When the hydraulic drive unit 20 is disconnected from both the replenishment oil circuit module 60 and the drive oil circuit module 40, in response to the oil pressure in the slip control oil circuit 110 exceeding a first pressure threshold, hydraulic oil can flow through the slip control oil circuit 110 through the inlet and outlet of the hydraulic drive unit 20. This allows the hydraulic drive unit 20 to retain its rotational capability when yawing to a designated position, thereby driving the nacelle to slip and generating a radial force to achieve flexible unloading of the tower 200 and protect the tower structure. The first pressure threshold is the minimum starting pressure of the slip control oil circuit 110 and is less than the minimum pressure required for the hydraulic yaw system to maintain normal nacelle yaw.

[0068] In these embodiments, when the nacelle yaws to the designated position, the output shaft of the hydraulic drive unit 20 is not completely braked by mechanical braking. Instead, the connections between the replenishment oil circuit module 60, the drive oil circuit module 40, and the hydraulic drive unit 20 are disconnected respectively. The nacelle slippage is controlled based on the independently controlled slip control oil circuit 110 (hydraulic bypass). A small amount of hydraulic oil in the slip control oil circuit 110 is used to achieve flexible unloading of the tower. Specifically, when the nacelle yaws to the designated position, there may be residual stress or impact load between the nacelle and the tower 200. Flexible unloading (such as slowly releasing pressure) is required to protect the tower structure. At this time, the oil pressure of the slip control oil circuit 110 needs to be lower than the normal yaw drive pressure to avoid secondary impact on the tower. Among them, the first pressure threshold is less than the oil pressure value required for active yaw of the engine room. In other words, the oil pressure value during active yaw is higher than the first pressure threshold. When the oil pressure of the hydraulic drive unit 20 is higher than the first pressure threshold and lower than the minimum pressure value required for the hydraulic yaw system to maintain normal yaw of the engine room, the slip control oil circuit 110 can be triggered to achieve "high pressure drive and low pressure unloading" to meet different working conditions.

[0069] During operation, when the oil pressure in the slip control circuit 110 exceeds the first pressure threshold, the on / off state of the slip control circuit 110 is adjusted by hydraulic drive. This provides a certain hydraulic damping for the slip movement of the nacelle, preventing stalling or impact during free rotation and ensuring a smooth and controllable slip process. Furthermore, in slip mode, the hydraulic oil continuously circulates in the loop formed by the hydraulic drive unit 20 (hydraulic motor) and the slip control circuit, preventing damage to the hydraulic drive unit 20 (hydraulic motor) due to dry friction or lack of oil, thus providing necessary protection for the yaw safety of the wind turbine generator set.

[0070] In some embodiments, the slip control oil circuit 110 includes a second valve body 112 and a first relief valve 113, which are connected in series between the inlet and outlet of the hydraulic drive unit 20. The pressure setting value of the second valve body 112 is equal to the first pressure threshold. When the pressure difference between the inlet and outlet of the hydraulic drive unit 20 exceeds the pressure setting value of the first relief valve 113, the second valve body 112 opens and the first relief valve 113 overflows to circulate oil to the hydraulic drive unit 20.

[0071] In these embodiments, when the nacelle yaws to a designated position, the hydraulic drive unit 20 is disconnected from the replenishment oil circuit module 60 and the drive oil circuit module 40, and the second valve body 112 is in the open state. The first pressure threshold is lower than the minimum pressure value required for the hydraulic yaw system to maintain normal nacelle yaw. The pressure setting value of the first relief valve 113 is equal to the first pressure threshold. In use, the torque generated by the wind-driven hydraulic drive unit 20 forms pressure in the slip control oil circuit 110. When the pressure exceeds the first pressure threshold, the first relief valve 113 opens, forming circulating oil in the slip control oil circuit 110, causing the hydraulic drive unit 20 to start slipping until the pressure drops back to not exceed the first pressure threshold. This allows the nacelle to be slipped even when the nacelle cannot start yaw, thus completing the flexible unloading of the tower.

[0072] According to this application, the hydraulic yaw system also includes a hydraulic pressure protection unit 120, which is connected in parallel with the slip control oil circuit 110 and operates separately from it, so that the pressure difference between the inlet and outlet of the hydraulic drive unit 20 does not exceed a second pressure threshold. It should be noted that the second pressure threshold setting is greater than the first pressure threshold mentioned above. This setting effectively prevents the pressure in the hydraulic yaw system from exceeding its maximum withstand pressure threshold, thereby ensuring the safety of the entire hydraulic yaw system during operation.

[0073] In this application, the first pressure threshold is the minimum starting pressure of the slip control oil circuit 110, and the second pressure threshold is the maximum permissible pressure value of the hydraulic yaw system. The first pressure threshold serves as the set pressure of the first relief valve 113, and is lower than the oil pressure value required for normal yaw of the engine room. The oil pressure value required for normal yaw of the engine room is the minimum permissible pressure of the hydraulic yaw system during normal yaw. Based on the setting that the first pressure threshold is lower than the oil pressure value required for normal yaw of the engine room, the engine room can slip when yawing to a designated position. Since the first pressure threshold, the oil pressure value required for normal yaw of the engine room, and the oil pressure value for engine room overspeed control are all lower than the second pressure threshold, it can be ensured that the corresponding operations for slip, normal yaw, and yaw overspeed are all performed under the condition of meeting system safety.

[0074] As a specific example, the hydraulic pressure protection unit 120 includes a second relief valve 122. The set pressure value of the second relief valve 122 is equal to a second pressure threshold, and it can overflow in response to the pressure difference between the inlet and outlet of the hydraulic drive unit 20 exceeding the set pressure value of the second relief valve 122. Furthermore, it can remain closed as long as the pressure difference between the inlet and outlet of the hydraulic drive unit 20 does not exceed the second pressure threshold of the second relief valve 122. Through this overflow mechanism, excess hydraulic energy in the hydraulic yaw system can be released in a timely manner, the pressure difference can be controlled within a safe range, damage to various components of the hydraulic yaw system due to excessive pressure can be avoided, and the stable and reliable operation of the system can be ensured.

[0075] According to this application, the hydraulic yaw system further includes a hydraulic brake unit 30 and a brake oil circuit module 50. The hydraulic brake unit 30 is located on one side of the hydraulic drive unit 20. The brake oil circuit module 50 connects the hydraulic oil tank 10 and the hydraulic brake unit 30, and can supply oil to the hydraulic brake unit 30 to disconnect the hydraulic drive unit 20 from the hydraulic brake unit 30. This avoids unnecessary resistance from the hydraulic brake unit 30 to the hydraulic drive unit 20, ensuring that the hydraulic drive unit 20 can efficiently drive the hydraulic yaw system to rotate, achieving accurate yaw control and improving the operating efficiency of the hydraulic yaw system. Furthermore, the brake oil circuit module 50 can cut off the oil supply to the hydraulic brake unit 30 to connect the hydraulic drive unit 20 and the hydraulic brake unit 30, generating braking force so that the hydraulic yaw system can quickly stop rotating when needed (e.g., in an emergency), ensuring the safety and stability of the hydraulic yaw system.

[0076] In some embodiments of this application, the oil supply to the hydraulic brake unit 30 can be controlled via the brake oil circuit module 50 to correlate the braking force with the braking timing. For example, in an emergency, the oil supply can be cut off to allow the hydraulic brake unit 30 to obtain maximum braking force, thereby stopping the movement of the hydraulic drive unit 20 and preventing safety accidents caused by excessive yaw or loss of control. During normal parking or yaw angle adjustment, the oil supply can be gradually cut off as needed to achieve smooth braking of the hydraulic drive unit 20.

[0077] In the existing technology, during the operation of wind turbine generators, the power supply may be interrupted due to various emergencies, such as grid failures or extreme weather (typhoons). In such cases, the brakes are often locked in the state of the hydraulic motor, which will limit the operation of the hydraulic yaw system under these circumstances.

[0078] Therefore, in order to ensure that the wind turbine generator can operate without being restricted by the brake when there is no power supply, according to this application, it is necessary to adjust the brake oil circuit module 50 when there is no power supply to the wind turbine generator.

[0079] In some embodiments, the brake hydraulic circuit module 50 includes a control valve 51, a backup power supply, and an accumulator 54. The control valve 51 is used to disconnect or connect the hydraulic drive unit 20 and the hydraulic brake unit 30; the backup power supply is connected to the control valve 51; the accumulator 54 is connected between the control valve 51 and the hydraulic oil tank 10, and the accumulator can supply oil to the hydraulic brake unit 30 through the control valve 51. In the event of no power supply to the wind turbine generator set, the backup power supply can supply power to the control valve 51, so that the control valve 51 is in an open state, thereby supplying oil to the hydraulic drive unit 20 through the accumulator 54, thus disconnecting the hydraulic drive unit 20 and the hydraulic brake unit 30. In this way, the hydraulic yaw system will not become uncontrollable due to power failure, avoiding serious safety accidents such as equipment damage and blade collision caused by the lack of effective measures to deal with power failure, and providing a solid guarantee for the safe operation of the wind turbine generator set.

[0080] In a specific example, when oil is supplied to the hydraulic drive unit 20 through the accumulator 54, in order to prevent the hydraulic oil from flowing back to the hydraulic oil tank 10, a check valve can be installed between the hydraulic oil tank 10 and the accumulator 54 to suppress the flow of hydraulic oil from the accumulator 54 to the hydraulic oil tank 10.

[0081] According to this application, a hydraulic yaw system is provided. This hydraulic yaw system can realize active yaw with electricity, yaw overspeed control, yaw slip, and passive yaw without electricity when the hydraulic brake 30 is released. It can also be restricted in movement when the hydraulic brake 30 is locked.

[0082] The following will describe the various operating conditions of the hydraulic yaw system.

[0083] like Figure 1 As shown, the tower 200 is connected to the yaw gear ring 210 and is a fixed structure. The reducer is mounted on the base 300 (equivalent to the engine room). The hydraulic drive unit 20 (hydraulic motor) is mounted on the reducer 220. The reduction gear 230 of the reducer 220 rotates around the yaw gear ring 210, thereby driving the engine room to rotate around the axis of the tower 200. The hydraulic drive unit 20 (hydraulic motor) serves as the power source, driving the input shaft of the reducer 220 to rotate via hydraulic oil pressure, which in turn drives the reduction gear 230 of the reducer 220 to revolve around the yaw gear ring 210.

[0084] According to this application, the hydraulic drive unit 20 is a hydraulic motor, and a hydraulic brake unit 30 is provided on the output shaft of the hydraulic motor. The hydraulic brake unit 30 is used to lock the hydraulic drive unit 20 or release the lock on the hydraulic drive unit 20.

[0085] Figure 3 This is a schematic diagram illustrating the disconnection between the hydraulic drive unit and the hydraulic braking unit of the hydraulic yaw system provided according to an embodiment of the present invention. Figure 3 As shown, the hydraulic braking unit 30 can disconnect or connect to the hydraulic drive unit 20 under the action of the corresponding brake oil circuit module 50, thereby enabling corresponding operations based on the corresponding working conditions. For example, the hydraulic braking unit 30 can be reliably released before yaw operation.

[0086] When the hydraulic yaw system of the wind turbine generator set needs to perform yaw operation, the motor is first started to rotate, driving the pumping device 100 to rotate (operate). At this time, the loading valve 130 is energized and in a non-conducting state, and the directional adjustment valve 41 is de-energized and in a non-conducting state. Figure 3 As shown, the hydraulic oil pumped from the pumping device 100 provides high pressure to the control valve 51 and the accumulator 54 via the fifth passage 52. When the control valve 51 is energized and in the conducting state, the high-pressure oil generated by the accumulator 54 or the pump enters the hydraulic braking unit 30 via the sixth passage 53, compressing the spring inside the hydraulic braking unit 30. The hydraulic braking unit 30 is then released, releasing the brake on the output shaft of the hydraulic drive unit 20, allowing the hydraulic drive unit 20 to rotate freely and enabling yaw action. Conversely, when the control valve 51 is de-energized and in the non-conducting state, the hydraulic braking unit 30 is not hydraulically driven, and under the force of the spring, it brakes the output shaft of the hydraulic drive unit 20, preventing the hydraulic drive unit 20 from rotating.

[0087] According to this application, after the hydraulic brake 30 is released, the hydraulic drive 20 is allowed to rotate freely, enabling the wind turbine generator to perform active yaw under strong wind conditions. Depending on the yaw direction requirement, either solenoid valve a or solenoid valve b of the directional control valve 41 is energized to perform active yaw. Specifically, when the electromagnet of solenoid valve a of the directional control valve 41 is energized, the directional control valve 41 operates in the left-hand position. At this time, the first working port P and the fourth working port B of the directional control valve 41 are connected, and the second working port T and the third working port A are connected. The hydraulic oil flows sequentially from the hydraulic oil tank, the pumping device 100, the first working port P, the fourth working port B, the fourth passage 46 of the directional control valve 41, the hydraulic drive 20, the third passage 45, the third working port A, the second working port T of the directional control valve 41, the flow rate regulating unit 44, and back to the hydraulic oil tank, forming a closed loop. When the electromagnet of solenoid valve b of the directional control valve 41 is energized, the directional control valve 41 operates in the right-hand position. At this time, the first working port P and the third working port A of the directional regulating valve 41 are connected, and the second working port T and the fourth working port B are connected. At this time, the hydraulic oil circuit flows sequentially from the hydraulic oil tank, the pumping device 100, the first working port P, the third working port A, the third passage 45 of the directional regulating valve 41, the hydraulic drive unit 20, the fourth passage 46, the fourth working port B, the second working port T of the directional regulating valve 41, the flow rate regulating unit 44, and back to the hydraulic oil tank to form a closed loop.

[0088] Through the different oil passages described above, high-pressure oil can enter the corresponding oil port of the hydraulic drive unit 20, driving it to rotate in the corresponding direction, such as clockwise or counterclockwise. The hydraulic drive unit 20 drives the reduction gear 230 through the reducer 220. The reduction gear 230 rotates relative to the yaw gear ring 210 fixed on the tower 200, thereby driving the entire nacelle to rotate to achieve active yaw.

[0089] Furthermore, during active yaw, hydraulic oil from the hydraulic tank is pumped into the drive oil circuit module 40 via the pumping device 100. At this time, the rotating part 71 is not required for oil supply. Therefore, the rotating part 71 is separated from the hydraulic drive unit 20 by controlling the connecting structure 72 (clutch) via the control unit. In other words, during active yaw, the rotation of the hydraulic drive unit 20 does not drive the rotating part 71 to rotate.

[0090] In some embodiments, the hydraulic yaw system further includes a system relief valve disposed between the pumping device 100 and the hydraulic oil tank 10, for ensuring that the hydraulic yaw system can operate safely without exceeding the hydraulic yaw system pressure threshold.

[0091] According to this application, the hydraulic yaw system can also execute a response plan corresponding to yaw overspeed. In an exemplary embodiment, when the control unit detects that the rotational speed of the hydraulic drive unit 20 exceeds the rated speed, it needs to increase the pressure at the return port of the hydraulic drive unit 20. By providing resistance through the hydraulic drive unit 20 (setting the driving force direction to be opposite to the external force direction), the speed is reduced, thereby preventing damage to the hydraulic drive unit 20. Specifically, when the rotational speed of the hydraulic drive unit 20 exceeds the rated speed, the opening of the valve of the flow rate regulating unit 44 is reduced to increase the pressure at the outlet of the hydraulic drive unit 20, allowing the hydraulic drive unit 20 to provide resistance and reduce the yaw speed. At this time, the state of the oil circuit is as follows: Figure 5 As shown, the opening of the oil inlet is not reduced, so the oil flow rate is not affected, and the hydraulic drive unit 20 will not idle. A throttling scheme is implemented by using a directional adjustment valve 41 and a flow rate adjustment unit 44 in the return oil circuit (second passage 43). Specifically, the yaw direction is switched only by the directional adjustment valve 41, and the flow rate adjustment unit 44 controls the speed when overspeeding. This provides reliable resistance to suppress overspeed without affecting the performance of the hydraulic drive unit 20.

[0092] It should be noted that during the yaw overspeed control process, the provided oil pressure can be further increased through the accumulator 54.

[0093] When the wind direction sensor detects that the nacelle is aligned with the wind direction, the control unit issues a stop command. The directional adjustment valve 41 is de-energized and returns to the neutral position, cutting off the operation of the drive oil circuit module. When encountering wind speeds lower than the yaw requirement, the hydraulic yaw system can also slide to achieve flexible unloading of the tower after yaw positioning, protecting the tower structure.

[0094] In the specific design, when the engine room yaws to the designated position, the pumping device 100 stops supplying oil, the directional adjustment valve 41 is de-energized, the valve core is in the middle position, and ports A and B are blocked. Furthermore, the hydraulic brake 30 is released, the first valve body 631 is energized, causing the oil passage through the first valve body 631 to be blocked, and the second valve body 112 is energized, causing the oil passage through the second valve body 112 to be open. Therefore, the oil can be connected to the first relief valve 113.

[0095] like Figure 6 As shown, when the external force F1 is to the right, the hydraulic oil on the right side of the hydraulic drive unit 20 passes through the check valve 7.4 to the first relief valve 113 located on the second connecting pipe 111. When the pressure reaches the set pressure of the first relief valve 113, the first relief valve 113 opens, and the hydraulic oil passes through the check valve 7.1 to the left oil port of the hydraulic drive unit 20. Similarly, when the external force F1 is to the left, the oil passage on the left side of the hydraulic drive unit 20 passes through the check valve 7.3 to the first relief valve 113. When the pressure reaches the set pressure of the first relief valve 113, the first relief valve 113 opens, and the oil passes through the check valve 7.2 to the right oil port of the hydraulic drive unit 20.

[0096] The hydraulic yaw system according to this application can also execute response plans corresponding to safety warnings. In a specific example, the hydraulic yaw system may further include a second relief valve 122, which is disposed on the third connecting pipe 121. The set pressure of the second relief valve 122 is the limit pressure value of the hydraulic yaw system. It should be noted that the set pressure of the first relief valve 113 is different from the set pressure of the second relief valve 122, and is lower than the set pressure of the second relief valve 122.

[0097] As a specific example, the overflow pressure set for the second relief valve 122 is P1. That is, the second relief valve 122 will only open when the pressure at the upper oil port P of the second relief valve 122 reaches P1, and the second relief valve 122 will be closed when the pressure at the upper oil port P of the second relief valve 122 is lower than P1. When the first valve body 631 is energized, the oil passage through the first valve body 631 is blocked. When the second valve body 112 is not energized, the oil passage through the second valve body 112 is also blocked. When the pressure in the oil passage reaches or exceeds the limit pressure value of the hydraulic yaw system, high-pressure oil can pass through the check valve 7.3 to the second relief valve 122 to protect the hydraulic yaw system from damage due to excessive pressure.

[0098] When the wind turbine is without power (no power supply), the accumulator 54 stores sufficient hydraulic oil. The control valve 51 is energized by the backup power supply, causing the hydraulic brake 30 to release. It should be noted that the backup power supply is a pre-set independent power system, fundamentally different from the main power supply. For example, the backup power supply can be a battery bank or a diesel generator, while the main power supply is typically generated by the wind turbine. Furthermore, the hydraulic drive unit 20 is connected to the rotating unit 71 via a clutch. Figure 7 Under the action of the external force (direction F1), the hydraulic drive unit 20 rotates in the same direction as the external force, which drives the rotating unit 71 to rotate (see F3). The rotating unit 71 draws oil from the hydraulic oil tank 10 through the one-way valve 7.8 and flows to the inlet of the rotating unit 71 through the second node 142. After the oil from the rotating unit 71 reaches the third node 143, it flows to the one-way valve 7.5. When the pressure on the left side of the one-way valve 7.5 is higher than the pressure on the right side, oil is replenished to the inlet of the hydraulic drive unit 20. In addition, when the hydraulic drive unit 20 rotates, it promotes the flow of hydraulic oil to the hydraulic drive unit 20. In addition, in the absence of power, the first valve body 631 is de-energized and is in a conducting state, while the second valve body 112 is de-energized and is in a closed state. The hydraulic oil passes through the check valve 7.4 to the first valve body 631, connects to the hydraulic control throttle valve 632, and flows back to the hydraulic oil tank, forming an oil circuit circulation. This allows the hydraulic drive unit 20 to passively yaw at a certain pressure, and ensures the lubrication and reliability of the hydraulic yaw system during long-term yaw without power.

[0099] In these embodiments, in the event of a power outage (no power supply), the clutch is in the "engaged" state, connecting the hydraulic drive unit 20 and the rotating unit 71. When the external wind speed is high, the external wind drives the rotating hydraulic drive unit 20 to rotate in the same direction, thus replenishing oil from the hydraulic oil tank 10. This ensures sufficient oil supply to the hydraulic drive unit 20, enabling passive yaw without power and preventing damage to the hydraulic drive unit 20 due to lack of oil. Furthermore, under conditions of complete power shortage, passive yaw speed is controllable without human intervention or control, solving the problem of fan vibration in a simple and effective manner.

[0100] In a preferred embodiment, the hydraulic throttle valve 632 has the function of automatically adjusting its opening according to the hydraulic oil pressure, which can accurately respond to the wind speed requirements of passive yaw. The hydraulic throttle valve 632 has a spring on its right side and its left cavity connected to the first node 141, allowing hydraulic oil to be introduced at the first node 141. When encountering a large instantaneous external force, it can react quickly and automatically adjust its opening, effectively preventing excessive yaw speed. When the external force is small, the valve core can maintain a large opening, reducing resistance and improving yaw speed, making the system more flexible and efficient. Simultaneously, as the external force gradually increases, the hydraulic throttle valve will not completely close. This avoids the situation where passive yaw is impossible due to complete closure, and also avoids the impact caused by sudden valve closure, ensuring the smooth operation of the hydraulic yaw system.

[0101] Specifically, when the external force is large, the valve opening of the hydraulic throttle valve automatically decreases, providing greater resistance more quickly and preventing system malfunctions due to overspeed operation. When the external force is small, the valve opening increases, reducing resistance to ensure the hydraulic yaw system can perform passive yaw smoothly. Compared to a fixed-opening throttle valve (which has the problem that if the valve core opening is too small, the resistance provided is large, and passive yaw cannot be achieved with small external forces; if the valve core opening is too large, the resistance provided is small, and the passive yaw speed is too fast with large external forces), this avoids the problem of not being able to achieve passive yaw due to small external forces; and it reduces the risk of excessively fast and uncontrollable passive yaw speed caused by large external forces.

[0102] Furthermore, when the oil flows through the hydraulic throttle valve 632, the throttling effect generates heat, causing the oil temperature to rise. The heated oil then enters the drive motor 642 located on the first connecting pipe 641, where the drive motor 642 rotates and drives the fan 643 to rotate. Subsequently, the oil undergoes heat dissipation treatment as it passes through the radiator 644, effectively controlling the oil temperature and ensuring stable operation of the hydraulic yaw system in a suitable temperature environment.

[0103] According to a second aspect of this application, a wind turbine generator set is provided, comprising a tower 200 and a nacelle, the nacelle being mounted on the tower 200 and driven by the aforementioned hydraulic yaw system to achieve yaw. Specifically, the nacelle base 300 is mounted on the tower 200 via a yaw gear ring 210.

[0104] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A hydraulic yaw system for use in the nacelle of a wind turbine generator set, characterized in that, The hydraulic yaw system includes: Hydraulic oil tank (10); Hydraulic drive unit (20) for driving the cabin to rotate; The drive oil circuit module (40) connects the hydraulic oil tank (10) and the hydraulic drive unit (20) and is used to selectively supply hydraulic oil from the hydraulic oil tank (10) to the hydraulic drive unit (20); The oil replenishment drive unit (70) is selectively connected to the hydraulic drive unit (20); The fluid replenishment circuit module (60) is connected to the oil replenishment drive unit (70), the hydraulic drive unit (20), and the hydraulic oil tank (10). When the wind turbine generator set has a power supply, the hydraulic drive unit (20) is disconnected from the oil replenishment drive unit (70) to form a hydraulic oil circuit through the drive oil circuit module (40) and the hydraulic drive unit (20); When the wind turbine generator set has no power supply, the hydraulic drive unit (20) is rotatably connected to the oil replenishment drive unit (70) to form an oil pressure circuit through the oil replenishment circuit module (60) and the oil replenishment drive unit (70).

2. The hydraulic yaw system according to claim 1, characterized in that, The fluid replenishment circuit module (60) includes: A flow regulating unit (63) is disposed between the output end of the hydraulic drive unit (20) and the hydraulic oil tank (10); The flow regulation unit (63) can reduce the flow rate of hydraulic oil flowing through the hydraulic drive unit (20) at the next moment if the rotational speed of the hydraulic drive unit (20) at the current moment is greater than a first preset threshold; or, The flow rate regulating unit (63) can increase the flow rate of hydraulic oil flowing through the hydraulic drive unit (20) at the next moment, provided that the rotation speed of the hydraulic drive unit (20) at the current moment is not greater than a first preset threshold.

3. The hydraulic yaw system according to claim 2, characterized in that, The flow regulation unit (63) includes: A hydraulic throttle valve (632) is disposed between the output end of the oil replenishment drive unit (70) and the hydraulic oil tank (10).

4. The hydraulic yaw system according to claim 3, characterized in that, The flow regulation unit (63) further includes: The first valve body (631) is disposed adjacent to the hydraulic throttle valve (632) between the output end of the oil replenishment drive unit (70) and the hydraulic oil tank (10). When the wind turbine generator set has no power supply, the first valve body (631) is in the open state, and the valve opening of the hydraulic throttle valve (632) decreases in response to the increase of the rotation speed of the hydraulic drive unit (20) being greater than a first preset threshold.

5. The hydraulic yaw system according to claim 1, characterized in that, The oil replenishment drive unit (70) includes: The rotating part (71) is connected to the hydraulic oil tank (10) and the replenishing oil circuit module (60). The connecting structure (72) can selectively connect the rotating part (71) and the hydraulic drive part (20). When the connecting structure (72) and the hydraulic drive unit (20) are connected, the hydraulic drive unit (20) can drive the rotating part (71) to rotate, thereby making the hydraulic drive unit (20) and the rotating part (71) rotatably connected, so as to drive the rotating part (71) to supply oil to the replenishing oil circuit module (60). When the connecting structure (72) and the hydraulic drive unit (20) are disconnected, the hydraulic drive unit (20) is disconnected from the rotating part (71), so as to disconnect the oil supply from the rotating part (71) to the replenishing oil circuit module (60).

6. The hydraulic yaw system according to claim 5, characterized in that, The connection structure (72) is a clutch that can disconnect the rotating part (71) and the hydraulic drive part (20) when the wind turbine generator set has power supply, and can connect the rotating part (71) and the hydraulic drive part (20) when the wind turbine generator set has no power; and / or, the rotating part (71) is a replenishing oil pump.

7. The hydraulic yaw system according to claim 1, characterized in that, The hydraulic drive unit (20) is at least one hydraulic motor.

8. The hydraulic yaw system according to claim 1, characterized in that, The drive oil circuit module (40) includes: Pumping device (100); Directional adjustment valve (41) connects the pumping device (100) and the hydraulic drive unit (20), and connects the hydraulic oil tank (10) and the hydraulic drive unit (20). A flow rate regulating unit (44) is disposed between the directional regulating valve (41) and the hydraulic oil tank (10); The hydraulic yaw system further includes a control unit, which is communicatively connected to the hydraulic drive unit (20) and the flow rate regulation unit (44); The control unit controls the flow rate regulating unit (44) to reduce the speed of the hydraulic drive unit (20) in response to the speed of the hydraulic drive unit (20) exceeding the speed threshold.

9. The hydraulic yaw system according to claim 8, characterized in that, The flow rate regulating unit (44) is a proportional throttle valve, which is located between the outlet of the directional regulating valve (41) and the hydraulic oil tank (10).

10. The hydraulic yaw system according to claim 9, characterized in that, The control unit (80) controls the opening degree of the proportional throttle valve to be not less than 90% in response to the fact that the rotational speed of the hydraulic drive unit (20) does not exceed a preset speed threshold.

11. The hydraulic yaw system according to claim 1, characterized in that, The hydraulic yaw system also includes: The slip control oil circuit (110) is connected to the inlet and outlet of the hydraulic drive unit (20). When the hydraulic drive unit (20) is disconnected from the replenishment oil circuit module (60) and the drive oil circuit module (40), in response to the oil pressure of the slip control oil circuit (110) exceeding the first pressure threshold, hydraulic oil can flow through the slip control oil circuit (110) through the inlet and outlet of the hydraulic drive unit (20) to make the hydraulic drive unit (20) rotate, thereby driving the cabin to slip.

12. The hydraulic yaw system according to claim 11, characterized in that, The slip control oil circuit (110) includes: The second valve body (112) and the first relief valve (113) are connected in series between the inlet and outlet of the hydraulic drive unit (20). The pressure setting value of the second valve body (112) is equal to the first pressure threshold. When the pressure difference between the inlet and outlet of the hydraulic drive unit (20) exceeds the pressure setting value of the first relief valve (113), the second valve body (112) opens and the first relief valve (113) overflows to circulate oil to the hydraulic drive unit (20).

13. The hydraulic yaw system according to claim 11, characterized in that, The hydraulic yaw system also includes: The hydraulic protection unit (120) is connected in parallel with the slip control oil circuit (110) and operates separately from the slip control oil circuit (110) so that the pressure difference between the inlet and outlet of the hydraulic drive unit (20) does not exceed the second pressure threshold, wherein the second pressure threshold is greater than the first pressure threshold.

14. The hydraulic yaw system according to claim 13, characterized in that, The hydraulic protection unit (120) includes: The second relief valve (122) is set at a pressure value equal to the second pressure threshold and overflows in response to the pressure difference between the inlet and outlet of the hydraulic drive unit (20) exceeding the set pressure value of the second relief valve (122).

15. The hydraulic yaw system according to any one of claims 1 to 14, characterized in that, The hydraulic yaw system also includes: A hydraulic braking unit (30) is provided on one side of the hydraulic drive unit (20); The brake oil circuit module (50) connects the hydraulic oil tank (10) and the hydraulic brake unit (30), and can supply oil to the hydraulic brake unit (30) to disconnect the hydraulic drive unit (20) from the hydraulic brake unit (30); and can cut off the oil supply to the hydraulic brake unit (30) to connect the hydraulic drive unit (20) to the hydraulic brake unit (30).

16. The hydraulic yaw system according to claim 15, characterized in that, The brake hydraulic circuit module (50) includes: A control valve (51) is used to disconnect or connect the hydraulic drive unit (20) and the hydraulic brake unit (30); A backup power supply is connected to the control valve (51); An accumulator (54) is connected between the control valve (51) and the hydraulic oil tank (10), and the accumulator can supply oil to the hydraulic braking unit (30) through the control valve (51); In the event that the wind turbine generator set is without power supply, the backup power supply can supply power to the control valve (51) so that the control valve (51) is in the open state, thereby supplying oil to the hydraulic drive unit (20) through the accumulator (54), so that the hydraulic drive unit (20) and the hydraulic brake unit (30) are disconnected.

17. A wind turbine generator set, characterized in that, The wind turbine generator set includes: Tower; The nacelle is mounted on the tower and is driven by a hydraulic yaw system according to any one of claims 1 to 16 to achieve yaw.

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