Wind turbine and hydraulic variable pitch system and control method thereof

Abstract

The present disclosure provides a wind turbine generator and a hydraulic variable pitch system and control method thereof. The hydraulic variable pitch system comprises: a variable pitch cylinder having a first chamber and a second chamber; a driving unit driving hydraulic oil to form a plurality of oil supply and return paths; a first electromagnetic valve connected between the variable pitch cylinder and the driving unit and simultaneously formed on the oil supply and return path of the second chamber and the oil supply and return path of the first chamber; a second electromagnetic valve connected between the first electromagnetic valve and the first chamber and arranged on the oil supply and return path of the first chamber; a first check valve connected between the first chamber and the oil supply port of the first electromagnetic valve and arranged on the second oil return path of the first chamber; wherein, in the normal shutdown working condition, before the piston rod of the variable pitch cylinder extends to a predetermined position, the first chamber releases hydraulic oil through the second oil return path, and when the piston rod of the variable pitch cylinder extends to or beyond the predetermined position, the first chamber releases hydraulic oil through the first oil return path.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind power generation, in particular to a wind turbine and a hydraulic variable pitch system and control method thereof. BACKGROUND

[0002] On the one hand, when the variable pitch system of the wind turbine is driven by hydraulic oil, an oil cylinder is generally used as an actuator. During variable pitch, the rotation of the variable pitch bearing is achieved by the extension and retraction of the oil cylinder piston rod, which in turn drives the rotation of the blade to change the pitch angle. In the hydraulic variable pitch system, the power of the hydraulic variable pitch system is as small as possible due to the constraints of the wind turbine, so the variable pitch system is generally made into a differential circuit, that is, when the second chamber of the oil cylinder is supplied with oil and the first chamber is discharged, the hydraulic oil in the first chamber will flow back to the second chamber of the oil cylinder, saving the supply of the oil cylinder or accumulator. However, the force arm of the oil cylinder will change with the length of the extension of the oil cylinder piston rod, so the maximum output torque of the oil cylinder is changing. For example, when the variable pitch angle is 90°, the force arm is the smallest, that is, the driving torque becomes smaller and smaller during the process of stopping the blade, and it may not be able to drive the blade.

[0003] On the other hand, during the hoisting of the wind turbine, the variable pitch system is executed to center the bolts on the blade with the bolt holes of the variable pitch bearing. The power source for the variable pitch action of the variable pitch system is often a temporary power source. However, if a temporary power source is used to drive the variable pitch system, and a fault occurs to cause the variable pitch system to be powered off, it will trigger emergency feathering of the variable pitch system, which will bring great risk to the unit, especially when single-blade hoisting is performed, which may cause the risk of blade falling. Using external equipment to drive the variable pitch system to change pitch can avoid the risk of triggering emergency feathering, but it requires additional design of related equipment and increases the installation and disassembly time of the external equipment during hoisting. SUMMARY

[0004] One of the purposes of the present application is to provide a hydraulic variable pitch system capable of increasing the driving force of the variable pitch oil cylinder.

[0005] One of the purposes of the present application is to provide a hydraulic variable pitch system capable of being used for blade hoisting.

[0006] According to a first aspect of the present disclosure, a hydraulic variable pitch system is provided, comprising: a variable pitch cylinder having a first chamber and a second chamber; a drive unit driving hydraulic oil in the hydraulic variable pitch system to form a plurality of oil supply and return paths; a first solenoid valve connected between the variable pitch cylinder and the drive unit and simultaneously formed on the oil supply and return path of the second chamber and the oil supply and return path of the first chamber, the oil supply and return path of the first chamber comprising a first return path, and the oil supply and return path of the second chamber comprising a first oil supply path; a second solenoid valve connected between the first solenoid valve and the first chamber and arranged on the oil supply and return path of the first chamber; a first check valve connected between the first chamber and the oil supply port of the first solenoid valve and arranged on a second return path of the first chamber, the second return path being different from the first return path; wherein, in a normal shutdown condition, before the piston rod of the variable pitch cylinder is extended to a predetermined position, the first chamber releases hydraulic oil through the second return path, and when the piston rod of the variable pitch cylinder is extended to or beyond the predetermined position, the first chamber releases hydraulic oil through the first return path.

[0007] According to a second aspect of the present disclosure, a wind turbine generator is provided, comprising the above-mentioned hydraulic variable pitch system.

[0008] According to a third aspect of the present disclosure, a control method of a hydraulic variable pitch system is provided, the hydraulic variable pitch system being as described above, the control method comprising: in response to a normal shutdown condition, before the piston rod of the variable pitch cylinder is extended to a predetermined position, controlling the first solenoid valve to be in a first working state and controlling the second solenoid valve to be in a first working state, so that the first chamber releases hydraulic oil through the second return path; when the piston rod of the variable pitch cylinder is extended to or beyond the predetermined position, controlling the first solenoid valve to be in the first working state and controlling the second solenoid valve to be in a second working state, so that the first chamber releases hydraulic oil through the first return path.

[0009] The hydraulic variable pitch system according to the embodiments of the present disclosure can improve the safety of the hydraulic variable pitch system.

[0010] The hydraulic variable pitch system according to the embodiments of the present disclosure can keep the unit in a safe state without triggering emergency feathering in the case of power failure of the system for hoisting, and is simple to operate and saves time. BRIEF DESCRIPTION OF DRAWINGS

[0011] The above and / or other aspects and advantages of the present disclosure will become more apparent by describing in detail embodiments thereof with reference to the attached drawings, in which:

[0012] Figure 1 is a schematic diagram of a hydraulic variable pitch system according to a first embodiment of the present disclosure;

[0013] Figure 2is a schematic diagram of a hydraulic variable pitch system according to a third embodiment of the present disclosure.

[0014] Figure 3 is a schematic diagram of a hydraulic variable pitch system according to a third embodiment of the present disclosure. DETAILED DESCRIPTION

[0015] The hydraulic variable pitch system according to embodiments of the present disclosure is used for normal pitch during in-service operation, for example, different hydraulic circuits can be activated or selected in normal shutdown working conditions, so that the variable pitch driving torque can be increased in the case of driving arm reduction, ensuring the normal operation of the system.

[0016] The hydraulic variable pitch system according to embodiments of the present disclosure can be used in feathering shutdown, and before the driving blade stops to the feathering position, the differential hydraulic circuit is closed and the oil return path of the first chamber to the oil tank is activated at the same time, so that the pressure difference between the second chamber and the first chamber is increased, thereby increasing the driving torque of the variable pitch cylinder in the final stage of driving the blade to feather, and performing normal feathering.

[0017] The hydraulic variable pitch system according to embodiments of the present disclosure can be used for lifting, and is especially suitable for performing lifting on a single blade, and the stop valve on the oil supply path of the second chamber specially set for lifting can be closed during lifting, thereby preventing the piston rod of the cylinder from being undesirably extended in the event of power failure, and improving operation convenience and safety.

[0018] Embodiments of the present disclosure will be described below with reference to the accompanying drawings, in which like reference numerals always indicate like parts.

[0019] Figure 1 is a schematic diagram of a hydraulic variable pitch system according to a first embodiment of the present disclosure, Figure 2 is a schematic diagram of a hydraulic variable pitch system according to a second embodiment of the present disclosure, Figure 3 is a schematic diagram of a hydraulic variable pitch system according to a third embodiment of the present disclosure.

[0020] According to embodiments of the present disclosure, the hydraulic variable pitch system comprises a variable pitch cylinder 8, a driving unit 1, a first electromagnetic valve 6, a second electromagnetic valve 7, and a first check valve 12.

[0021] As shown in Figures 1 to 3 The variable pitch cylinder 8 can have a first chamber and a second chamber. The second chamber can be a rodless chamber, and the first chamber can be a rod chamber. As an example, an elastic component such as a spring can also be arranged in the second chamber.

[0022] The rod of the variable pitch cylinder 8 can be connected to the piston of the variable pitch cylinder 8, and can be extended when the blade is feathered and retracted when the blade is pitched by the pressure difference between the second chamber and the first chamber.

[0023] The driving unit 1 can drive the hydraulic oil in the hydraulic variable pitch system to form a plurality of oil supply and return paths. The driving unit 1 is a component in the hydraulic system that can provide high pressure oil to drive the variable pitch cylinder to act.

[0024] For example, the driving unit 1 can include an accumulator, although not shown, and the hydraulic oil tank can be driven by the hydraulic pump to flow into the accumulator, and the driving unit 1 can also include auxiliary components such as a hydraulic pump.

[0025] As shown in Figure 1 and Figure 3 The first electromagnetic valve 6 can be connected between the variable pitch cylinder 8 and the driving unit 1 and simultaneously form the oil supply and return path of the second chamber and the oil supply and return path of the first chamber. That is, the first electromagnetic valve 6 can be formed on the common oil supply and return path of the second chamber and the first chamber. The oil supply and return path of the first chamber can include a first return path, and the oil supply and return path of the second chamber can include a first oil supply path.

[0026] The first electromagnetic valve 6 can be a single electromagnetic valve, or it can be a valve group formed by different electromagnetic valves. For example, when the first electromagnetic valve 6 is a valve group, the first electromagnetic valve 6 can include a plurality of electromagnetic valves, a part of the electromagnetic valves can be arranged on the oil supply and return path of the second chamber to selectively activate the oil supply and return path of the second chamber, and another part of the electromagnetic valves can be arranged on the oil supply and return path of the first chamber to selectively activate the oil supply and return path of the first chamber.

[0027] In addition, the first electromagnetic valve 6 can also be a single electromagnetic valve, for example, the first electromagnetic valve 6 can be a multi-position multi-way electromagnetic valve, specifically, the first electromagnetic valve 6 can be a three-position four-way electromagnetic valve, a three-position five-way electromagnetic valve, etc., as long as the second chamber can be supplied with oil through one path of the single electromagnetic valve and the first chamber can return oil through another path of the single electromagnetic valve.

[0028] When the first electromagnetic valve 6 is a three-position four-way electromagnetic valve, the A port of the three-position four-way electromagnetic valve can be in communication with the second chamber, the B port of the three-position four-way electromagnetic valve can be in communication with the first chamber, the P port of the three-position four-way electromagnetic valve as the oil supply port can be in communication with the driving unit 1, and the T port of the three-position four-way electromagnetic valve as the oil return port can be in communication with the hydraulic oil tank 50 of the hydraulic variable pitch system.

[0029] According to an embodiment of the present application, the second electromagnetic valve 7 can be connected between the first electromagnetic valve 6 and the first chamber and can be arranged on the oil supply and return path of the first chamber. The second electromagnetic valve 7 can be bidirectional or unidirectional as needed, so that the oil return path of the first chamber through the first electromagnetic valve is selectively accessed to the oil circuit. For example, when the first chamber returns oil through the first return path, the second electromagnetic valve 7 can be turned on (bidirectional), and when the first chamber returns oil through other return paths, the second electromagnetic valve 7 can close the first return path.

[0030] For example, when normally pitching, the second electromagnetic valve 7 can be bidirectional, hydraulic oil can be supplied to the first chamber via the second electromagnetic valve 7 (at this time, pitching is performed), and the hydraulic oil of the first chamber can also be released via the second electromagnetic valve 7 (at this time, feathering is performed). Especially in the last stage of feathering shutdown, the second electromagnetic valve 7 can be switched from unidirectional to bidirectional, and the hydraulic oil of the first chamber can be switched to flow back to the hydraulic oil tank from the second electromagnetic valve 7 via other oil return paths.

[0031] As shown in Figure 1 and Figure 3 , the second electromagnetic valve 7 can be a two-position two-way electromagnetic valve, the B port of the two-position two-way electromagnetic valve can be in communication with the first chamber, and the A port of the two-position two-way electromagnetic valve can be in communication with the first electromagnetic valve 6. However, the present disclosure is not limited thereto, the second electromagnetic valve 7 can also be a valve group comprising electromagnetic valves, for example, the second electromagnetic valve can be realized by a combination of a one-way valve and an electromagnetic valve, the second electromagnetic valve can also be realized by multiple electromagnetic valves, and the second electromagnetic valve 7 can also be a multi-position multi-way electromagnetic valve, as long as the second electromagnetic valve 7 can activate the oil supply and return path of the first chamber, and can disconnect the oil return path of the first chamber through the second electromagnetic valve 7 when needed.

[0032] As shown in Figure 1 and Figure 3 , the A port of the first electromagnetic valve 6 as a three-position four-way electromagnetic valve can be in communication with the second chamber, the B port of the first electromagnetic valve as a three-position four-way electromagnetic valve can be in communication with the A port of the second electromagnetic valve 7 as a two-position two-way electromagnetic valve, the P port of the first electromagnetic valve 6 as a three-position four-way electromagnetic valve as an oil supply port can be in communication with the drive unit 1, the T port of the first electromagnetic valve 6 as a three-position four-way electromagnetic valve as an oil return port can be in communication with the hydraulic oil tank 50 of the hydraulic pitch system, and the B port of the second electromagnetic valve 7 as a two-position two-way electromagnetic valve can be in communication with the first chamber.

[0033] In the present disclosure, "A is in communication with B" includes two cases of A being directly in communication with B and other components being present between A and B.

[0034] As shown in Figure 1 and Figure 3 , the first one-way valve 12 can be connected between the first chamber and the oil supply port of the first electromagnetic valve 6 and arranged on the second oil return path of the first chamber. The second oil return path here is a different circuit path from the first oil return path of the first chamber mentioned above. The difference between the two paths means that at least one different component is arranged on the two paths through which the hydraulic oil flows.

[0035] The inlet of the first one-way valve 12 can be in communication with the first chamber, and the outlet of the first one-way valve 12 can be in communication with the oil supply port of the first electromagnetic valve 6.

[0036] As an example, a shut-off valve can also be provided on the oil supply and return path of the second chamber and the first chamber, facilitating use during maintenance.

[0037] According to an embodiment of the present disclosure, in the normal shutdown operating condition, the first chamber can release hydraulic oil via the second return oil path before the piston rod of the pitch cylinder 8 extends to a predetermined position, and the first chamber can release hydraulic oil via the first return oil path when the piston rod of the pitch cylinder 8 extends to or beyond the predetermined position.

[0038] Specifically, as shown in Figure 1 and Figure 3 , before the piston rod of the pitch cylinder 8 extends to a predetermined position, the first oil supply path of the second chamber can be: drive unit 1→P port of the first electromagnetic valve 6→A port of the first electromagnetic valve 6→second chamber, and the second return oil path of the first chamber can be: first chamber (rod cavity)→first check valve 12→oil supply port of the first electromagnetic valve 6.

[0039] When the piston rod of the pitch cylinder 8 extends to or beyond the predetermined position, the first oil supply path of the second chamber can be: drive unit 1→P port of the first electromagnetic valve 6→A port of the first electromagnetic valve 6→second chamber, and the first return oil path of the first chamber can be: first chamber (rod cavity)→second electromagnetic valve 7→B port of the first electromagnetic valve 6→T port of the first electromagnetic valve 6→hydraulic oil tank 50.

[0040] As shown in Figure 1 and Figure 3 , according to an embodiment of the present disclosure, the hydraulic pitch system can further include a third electromagnetic valve 9, which can be connected between the first chamber and the return oil port of the first electromagnetic valve 6 and arranged on the third return oil path of the first chamber. The third return oil path of the first chamber is different from the first return oil path and the second return oil path.

[0041] Specifically, in the fault shutdown operating condition, the third electromagnetic valve 9 can be turned on to activate the third return oil path. The third electromagnetic valve 9 can be a normally closed electromagnetic valve. For example, the third electromagnetic valve 9 can be turned on or closed in the case of power loss, and the hydraulic oil in the first chamber can be quickly discharged to the hydraulic oil tank 50 via the third electromagnetic valve 9. Specifically, the third electromagnetic valve 9 can be bidirectional in the case of power loss, and can shut off the discharge oil path of the first chamber via the third return oil path in the case of power on.

[0042] The third electromagnetic valve 9 can be a two-position two-way electromagnetic valve, the A port of the two-position two-way electromagnetic valve can be in communication with the first chamber, the B port of the two-position two-way electromagnetic valve can be in communication with the return oil port of the first electromagnetic valve 6, and the return oil port of the first electromagnetic valve 6 can be in communication with the hydraulic oil tank for collecting low-pressure oil.

[0043] As an example, a second throttle valve 11 can also be provided on the third oil return path of the first chamber, the B port of the third solenoid valve 9 can be in communication with the inlet of the second throttle valve 11, and the outlet of the second throttle valve can be in communication with the hydraulic oil tank 50 or the oil return port of the first solenoid valve 6.

[0044] The oil supply port and the oil return port of the first solenoid valve 6 can be separated by a first stop valve 13, that is, the first stop valve 13 can be provided between the driving unit 1 as an accumulator and the T port of the first solenoid valve 6 as a three-position four-way solenoid valve, so as to separate the high-pressure oil provided by the driving unit 1 from the low-pressure oil collected by the hydraulic oil tank 50.

[0045] For the above-mentioned hydraulic system, the following control mode can be adopted: in response to a normal shutdown condition (feather), the first solenoid valve 6 can be controlled to be in a first working state (for example, before the piston rod of the variable pitch cylinder 8 is extended to a predetermined position (for example, 2 / 3 thread)) and the second solenoid valve can be controlled to be in a first working state, so that the hydraulic oil in the driving unit 1 is supplied to the second chamber via the first oil supply path, and the hydraulic oil in the first chamber is released via the first oil return path. Here, the different working states of the first solenoid valve 6 and the second solenoid valve 7 can be different power supply states of the first solenoid valve 6 and the second solenoid valve 7, and the different power supply states cause the two solenoid valves to be in different working states.

[0046] After the piston rod of the variable pitch cylinder 8 is extended to the predetermined position or beyond the predetermined position, the first solenoid valve 6 can be controlled to be in the first working state and the second solenoid valve can be controlled to be in the second working state, and the first chamber releases the hydraulic oil via the first oil return path.

[0047] Specifically, when the first solenoid valve 6 is in the first working state, the first solenoid valve adopts a first reversing path (from P→A, from B→T), and when the second solenoid valve 7 is in the first working state, the second solenoid valve 7 adopts a first reversing path (oil return path cut-off). When the second solenoid valve 7 is in the second working state, the second solenoid valve 7 adopts a second reversing path (bidirectional conduction path).

[0048] As an example, the working states of the first solenoid valve 6 and the second solenoid valve 7 can be controlled by the variable pitch controller 10, that is, the spool positions of the two solenoid valves can be controlled by controlling the power supply modes of the two solenoid valves by the variable pitch controller 10.

[0049] As shown in Figure 1 and Figure 3 The hydraulic variable pitch system can further include a variable pitch controller 10, which can control the first solenoid valve 6 and the second solenoid valve 7 to activate the oil supply and return paths of the second chamber and the first chamber.

[0050] The pitch controller 10 can be implemented by hardware such as an integrated circuit, or by a combination of hardware and software. Although the location of the specific controller is not shown in the drawings, the pitch controller can be provided in the nacelle as an example.

[0051] According to embodiments of the present disclosure, the hydraulic pitch system can also close a shut-off valve on a second oil supply path of the second chamber separately provided for hoisting during hoisting, thereby preventing the oil cylinder from being undesirably extended at power failure.

[0052] As shown in Figure 1 and 3 According to embodiments of the present disclosure, the hydraulic pitch system further includes a fourth electromagnetic valve 5 and a second shut-off valve 15 provided on a second oil supply path of the second chamber, where the second oil supply path of the second chamber can be different from the first oil supply path of the second chamber.

[0053] The inlet of the fourth electromagnetic valve 5 can be in communication with the drive unit 1, the outlet of the fourth electromagnetic valve 5 can be in communication with the inlet of the second shut-off valve 15, and the outlet of the second shut-off valve 15 can be in communication with the second chamber.

[0054] When the hydraulic pitch system according to embodiments of the present disclosure is used for blade hoisting, in the working condition of power failure of the hoisting tool, the fourth electromagnetic valve 5 can be turned on, and the second shut-off valve 15 is closed. The fourth electromagnetic valve 5 can be a normally closed electromagnetic valve, the fourth electromagnetic valve 5 can be unidirectionally turned on in the case of power-on, and the fourth electromagnetic valve 5 can be bidirectionally turned on in the case of power-off. As shown in Figure 3 The fourth electromagnetic valve 5 can be unidirectionally turned on together with the second check valve 4 to shut off the third oil supply path of the second chamber.

[0055] On the other hand, in the working condition of normal power generation and emergency feathering triggered, the fourth electromagnetic valve 5 is turned on and the second shut-off valve 15 is opened. For example, the fourth electromagnetic valve 5 can be bidirectionally turned on in the case of power-off.

[0056] As an example, the hydraulic pitch system can further include a first throttle valve 3 and a second check valve 4 provided on the second oil supply path of the second chamber, the inlet of the first throttle valve 3 can be in communication with the drive unit 1, the outlet of the first throttle valve 3 can be in communication with the inlet of the second check valve 4, and the outlet of the second check valve 4 can be in communication with the inlet of the fourth electromagnetic valve 5.

[0057] In one example, the second shut-off valve 15 can be provided with a position sensor, and when normal pitch is performed, the position of the valve core of the second shut-off valve 15 can be determined through the position sensor of the second shut-off valve, so as to ensure that the second shut-off valve 15 remains in the closed state.

[0058] As shown in Figure 1As shown, according to the embodiment of the present disclosure, the hydraulic variable pitch system can further include a first overflow valve 2 and a second overflow valve 14, the first overflow valve 2 can be arranged between the drive unit 1 and the second chamber of the variable pitch cylinder 8, and the second overflow valve 14 can be arranged between the drive unit 1 and the oil supply port of the first electromagnetic valve 6.

[0059] In addition to the above-mentioned components, the hydraulic variable pitch system can further include other auxiliary components. As shown in FIG. 1, the hydraulic variable pitch system can further include a hydraulic oil tank 10, a first electromagnetic valve 6, a second electromagnetic valve 7, a variable pitch cylinder 8, a first check valve 9, a second check valve 11, a third check valve 21, and a fourth check valve 22. Figure 3 Figure 2 Figure 3 Figures 1 to 3 Figure 2 As shown, the hydraulic variable pitch system can further include a third stop valve 21 and a fourth stop valve 22.

[0060] The third stop valve 21 can be arranged on the common path of different oil supply paths of the second chamber, and the fourth stop valve 22 can be arranged on the common path of different oil return paths of the first chamber.

[0061] An oil return filter can be arranged on the oil return path of the hydraulic oil tank, and an oil supply filter can be arranged on the oil supply path of the hydraulic oil tank, or an empty filter can be arranged on the hydraulic oil tank.

[0062] It should be noted that although not shown in the drawings, the embodiment of the present disclosure can include other various auxiliary components (such as stop valves, check valves, pressure sensors, oil filters, etc.).

[0063] The hydraulic variable pitch system according to the embodiment of the present disclosure can activate or select different hydraulic circuits under normal shutdown conditions, so that the variable pitch driving torque can be increased when the driving arm is reduced, and the normal operation of the system is ensured.

[0064] The hydraulic variable pitch system according to the embodiment of the present disclosure can close the differential hydraulic circuit and activate the oil return path between the first chamber and the oil tank before the driving blade stops at the feathering position when feathering, so that the pressure difference between the second chamber and the first chamber is increased, thereby increasing the driving torque of the variable pitch cylinder in the final stage of the driving blade feathering, and performing normal feathering.

[0065] The above only describes the preferred embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto, and any changes or replacements (for example, the features of different embodiments of the present disclosure can be combined) within the technical range disclosed in the present disclosure can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A hydraulic pitch control system, characterized in that, include: The pitch cylinder (8) has a first chamber and a second chamber; The drive unit (1) drives the hydraulic oil in the hydraulic pitch system to form multiple supply and return oil paths; The first solenoid valve (6) is connected between the pitch cylinder (8) and the drive unit (1) and is formed on both the oil supply and return path of the second chamber and the oil supply and return path of the first chamber. The oil supply and return path of the first chamber includes the first return path, and the oil supply and return path of the second chamber includes the first supply path. The second solenoid valve (7) is connected between the first solenoid valve (6) and the first chamber and is located on the first return oil path of the first chamber; The first one-way valve (12) is connected between the first chamber and the oil supply port of the first solenoid valve (6) and is located on the second oil return path of the first chamber. The second oil return path is different from the first oil return path. Under normal shutdown conditions, before the piston rod of the pitch cylinder (8) extends to a predetermined position, the first chamber releases hydraulic oil via the second return path. When the piston rod of the pitch cylinder (8) extends to or beyond the predetermined position, the first chamber releases hydraulic oil via the first return path. The hydraulic pitch system further includes a fourth solenoid valve (5) and a second shut-off valve (15) disposed on the second oil supply path of the second chamber. The inlet of the fourth solenoid valve (5) is connected to the drive unit (1), and the outlet of the fourth solenoid valve (5) is connected to the inlet of the second shut-off valve (15). The outlet of the second shut-off valve (15) is connected to the second chamber. The second oil supply path is different from the first oil supply path. In the case of power failure of the hoisting equipment, the fourth solenoid valve (5) is turned on and the second shut-off valve (15) is turned off. Under normal power generation and emergency feathering conditions, the fourth solenoid valve (5) is turned on and the second shut-off valve (15) is opened.

2. The hydraulic pitch system according to claim 1, characterized in that, The hydraulic pitch system also includes a third solenoid valve (9), which is connected between the first chamber and the return port of the first solenoid valve (6) and is located on the third return path of the first chamber. In the event of a fault shutdown, the third solenoid valve (9) is turned on to activate the third return path, which is different from both the first and second return paths.

3. The hydraulic pitch system according to claim 2, characterized in that, The third solenoid valve (9) is a two-position two-way solenoid valve. Port A of the third solenoid valve (9) is connected to the first chamber, and port B of the third solenoid valve (9) is connected to the return oil port of the first solenoid valve (6).

4. The hydraulic pitch system according to claim 1, characterized in that, The second solenoid valve (7) is a two-position two-way solenoid valve. The B port of the second solenoid valve (7) is connected to the first chamber, and the A port of the second solenoid valve (7) is connected to the first solenoid valve (6).

5. The hydraulic pitch system according to claim 4, characterized in that, The first solenoid valve (6) is a three-position four-way solenoid valve. The A port of the first solenoid valve (6) is connected to the second chamber. The B port of the first solenoid valve (6) is connected to the A port of the second solenoid valve (7). The P port of the first solenoid valve (6) is connected to the drive unit (1) as an oil supply port. The T port of the first solenoid valve (6) is connected to the hydraulic oil tank (50) of the hydraulic pitch system as a return oil port.

6. The hydraulic pitch system according to claim 5, characterized in that, The drive unit (1) includes an energy accumulator, which is connected to the P port of the first solenoid valve (6), and a first shut-off valve (13) is provided between the energy accumulator and the T port of the first solenoid valve (6).

7. The hydraulic pitch system according to claim 1, characterized in that, The hydraulic pitch system further includes a first throttle valve (3) and a second check valve (4) disposed on the second oil supply path in the second chamber. The inlet of the first throttle valve (3) is connected to the drive unit (1), the outlet of the first throttle valve (3) is connected to the inlet of the second check valve (4), and the outlet of the second check valve (4) is connected to the inlet of the fourth solenoid valve (5).

8. The hydraulic pitch system according to any one of claims 1 to 7, characterized in that, The hydraulic pitch system further includes a pitch controller configured to control the first solenoid valve (6) and the second solenoid valve (7) to activate the supply and return oil paths of the first chamber and the second chamber.

9. A wind turbine generator set, characterized in that, Includes the hydraulic pitch system according to any one of claims 1 to 8.

10. A control method for a hydraulic pitch system, characterized in that, The hydraulic pitch system is the hydraulic pitch system according to any one of claims 1-8, and the control method includes: In response to normal shutdown conditions, before the piston rod of the pitch cylinder (8) extends to a predetermined position, the first solenoid valve (6) is controlled to be in the first working state and the second solenoid valve (7) is controlled to be in the first working state, so that the first chamber releases hydraulic oil through the second return oil path; When the piston rod of the pitch cylinder (8) extends to or beyond a predetermined position, the first solenoid valve (6) is controlled to be in a first working state and the second solenoid valve (7) is controlled to be in a second working state, so that the first chamber releases hydraulic oil through the first return oil path.

Images