Electro-hydraulic servo pitch system for wind turbine generator set and implementation method thereof

Abstract

The present invention provides an electro-hydraulic servo pitch system for a wind turbine generator and an implementation method thereof, which includes an electro-hydraulic servo system, a servo oil cylinder, and a pitch structure; the pitch structure has a spherical structure, the spherical structure has a mounting opening, the mounting opening has a rotating piece and a fixed point, the rotating piece is rotatably arranged on the mounting opening, the fixed point is fixedly arranged at the edge of the mounting opening, the rotating piece is connected to the blade, the electro-hydraulic servo system and the servo oil cylinder are arranged on the fixed point, the tail of the oil chamber cylinder body of the servo oil cylinder is hinged to the fixed point, and the telescopic rod of the servo oil cylinder is hinged to the rotating piece. An electro-hydraulic servo pitch solution is provided, which maintains the characteristics of flexible servo electric action control and small volume, and introduces a closed hydraulic system, eliminating the oil source pump station and having extremely few pipeline components, thereby bringing extremely low leakage points, saving installation space, and having a great cost advantage.

Description

Technical Field

[0001] The present invention relates to a set of wind power pitch control systems, and more particularly to an electro-hydraulic servo pitch control system for wind turbines and its implementation method. Background Art

[0002] In existing wind turbines, pitch control is mostly implemented using an electric motor-driven pitch solution or a hydraulic cylinder-driven solution.

[0003] For the electric pitch control system solution, a servo motor is directly used to drive the reduction gearbox, which in turn drives the blade gear ring to achieve pitch control. In combination with an angle sensor / encoder, closed-loop angle control of the blade is realized; three blades, three electric drive devices.

[0004] For the hydraulic cylinder-driven solution, power is provided by an open-loop fixed-displacement pump station and an accumulator. A proportional directional valve is used to drive the cylinder to push the blade bearing to rotate; three groups of drive devices on three sides, each group consisting of two cylinders arranged in parallel and in a diagonal structure. The cylinder is matched with a displacement sensor to form a closed-loop angle control with the proportional valve.

[0005] The traditional electric pitch solution uses a pure mechanical transmission to drive the reduction gearbox to rotate. However, due to the operating environment, there will be a large impact on the gear, and the rigid structure has poor seismic resistance, resulting in serious wear of the gear ring; the backlash increases, which in turn leads to a delay or even failure of the pitch response, short service life of the gear ring, and extremely high maintenance costs.

[0006] The traditional hydraulic pitch control system is mostly an open-loop system, which requires a pump station, a proportional control valve group, etc. There are many components, large volume, intricate connecting pipelines, high manufacturing and assembly requirements, and a complex system; this brings many leakage points, high costs, and difficulties in maintenance. Summary of the Invention

[0007] To solve the problems existing in the above technologies, the present invention provides a device with a simple structure and more reasonable control of the blade angle.

[0008] An electro-hydraulic servo pitch control system for a wind turbine provided by the present invention includes an electro-hydraulic servo system, a servo cylinder, and a pitch structure;

[0009] The electro-hydraulic servo system has a servo motor and a hydraulic pump. The hydraulic pump has a two-way pressure output function, and the servo motor is used to control the delivery of the power oil of the hydraulic pump;

[0010] The servo cylinder has a displacement sensor, which is used to monitor the stroke of the telescopic rod of the servo cylinder. The oil chamber cylinder body of the servo cylinder is connected to the hydraulic pump, and the servo cylinders are arranged in an even number of pairs in series;

[0011] The pitch structure has a spherical structure, the spherical structure has a mounting opening, the mounting opening has a rotating piece and a fixed point, the rotating piece is rotatably arranged on the mounting opening, the fixed point is fixedly arranged at the edge of the mounting opening, the rotating piece is connected to the blade, the electro-hydraulic servo system and the servo oil cylinder are arranged on the fixed point, the tail of the oil chamber cylinder body of the servo oil cylinder is hinged to the fixed point, and the telescopic rod of the servo oil cylinder is hinged to the rotating piece.

[0012] A preferred solution is that the number of the servo oil cylinders is two groups, and the two groups of servo oil cylinders are symmetrically arranged on both sides of the rotating piece respectively, that is, the connection points of the two groups of servo oil cylinders to the rotating piece are symmetrically arranged with respect to the center position of the rotating piece.

[0013] A preferred solution is that the number of the servo oil cylinders is four groups, the servo oil cylinders include a first servo oil cylinder, a second servo oil cylinder, a third servo oil cylinder and a fourth servo oil cylinder, and the fixed points include a first fixed point and a second fixed point. The first servo oil cylinder and the second servo oil cylinder are arranged on the first fixed point, and the third servo oil cylinder and the fourth servo oil cylinder are arranged on the second fixed point. The telescopic rods of the first servo oil cylinder and the third servo oil cylinder are hinged to the first position point of the rotating piece, and the telescopic rods of the second servo oil cylinder and the fourth servo oil cylinder are hinged to the second position point. The first position point and the second position point are symmetrically arranged with respect to the center position point of the rotating piece, and the stroke controls of the first servo oil cylinder and the third servo oil cylinder are in a mutually exclusive relationship, while the stroke controls of the second servo oil cylinder and the fourth servo oil cylinder are in a mutually exclusive relationship.

[0014] A preferred solution is that there is also an external independent circulating cooling system, which is matched with a temperature monitoring sensor, and the circulating cooling system cools the servo motor and the hydraulic pump according to the heat generation requirement of the electro-hydraulic servo system.

[0015] A preferred solution is that the blade of the blade has a locking pin structure, and the locking pin structure is controlled by hydraulic transmission or electromagnetic braking.

[0016] A preferred solution is that the electro-hydraulic servo system has a safety overflow valve and a replenishing valve, and the replenishing valve is used to realize the functions of under-flow oil replenishment and excess flow overflow.

[0017] A preferred solution is that it also includes a control unit, the control unit is connected to the displacement sensor, the control unit records the angle of the blade of the blade according to the parameters obtained by the displacement sensor, and accordingly controls the servo oil cylinder to realize equal-volume closed-loop feedback control.

[0018] The implementation method of the electro-hydraulic servo pitch system for a wind turbine generator set provided by the present invention includes the following steps:

[0019] The servo motor drives the hydraulic pump to output a pressure oil source in a bidirectional high-frequency manner, and constitutes the power control unit of the closed system;

[0020] The power oil source enters one side of the hydraulic cylinder. The servo cylinder records the blade angle through a displacement sensor, and realizes equal-volume closed-loop feedback control when the servo cylinder acts;

[0021] The electro-hydraulic servo system is matched with a pressure sensor. According to the feedback of the pressure parameter and the displacement of the servo cylinder, a closed-loop control adjustment of the blade angle is constituted. The forward and reverse actions of the servo motor drive the extension and retraction of the cylinder, realizing the change of the blade angle.

[0022] The implementation method of the electro-hydraulic servo pitch system for a wind turbine generator set provided by the present invention includes the following steps: limiting the bidirectional pressure through a safety relief valve, and realizing the functions of under-flow oil replenishment and overflow of excess flow through an oil replenishing valve.

[0023] The beneficial effects of the present invention are as follows: an electro-hydraulic servo pitch scheme is provided, which maintains the characteristics of flexible servo electric action control and small volume, and introduces a closed hydraulic system, eliminating the oil source pumping station and having extremely few pipeline components, thus bringing extremely low leakage points, saving installation space and having a great cost advantage. At the same time, an equal-volume servo cylinder scheme is adopted, with small heat loss, low noise, and a compact structure, retaining the advantages of high hydraulic transmission efficiency and shock absorption and energy absorption, and extending the service life of structural components such as blades. The present invention also matches high-performance blade locks, emergency feathering, efficient heat dissipation and other systems to ensure the safety and reliability of the system.

[0024] An electro-hydraulic servo pitch system for a wind turbine generator set and its implementation method of the present invention include a complete set of servo electro-hydraulic control systems and pitch drive schemes, and the characteristics are as follows:

[0025] (1) An electro-hydraulic servo system is adopted, and the servo motor and the hydraulic pump cooperate to realize the output of a bidirectional pressure oil source with steplessly adjustable flow rate, constituting a servo hydraulic closed-loop system; the system can realize the four-quadrant high-frequency output of power.

[0026] (2) The pitch drive device is a uniquely designed low-liquid-resistance servo cylinder, including accurate displacement sensor feedback.

[0027] (3) The cylinder arrangement adopts a cylinder pair-out setting (the rodless cavity of one cylinder is connected in series with the rod cavity of another cylinder), realizing the equal-volume arrangement of the system flow rate, and further reducing the problems of large oil replenishment amount and large heat generation in the closed system caused by the volume difference. The cylinder arrangement is not limited to 2 pairs of arrangements, and even-numbered arrangements such as 4 pairs can also be realized. For the 2-pair arrangement method, please refer to Figure 5 andFigure 6 For the solution of Figure 4 , Figure 7 and Figure 8 , the solution of ; It is also possible to directly use an equal - volume double - rod cylinder for layout to achieve an equal - volume closed - loop circuit;

[0028] (4) Use a unique small - volume, low - pressure boost oil tank for oil replenishment in the closed - loop system;

[0029] An independent peripheral circulating cooling system is provided, and the system is matched with temperature monitoring. According to the heat generation requirement of the system, the pump and motor are cooled; not limited to forms such as air cooling and liquid cooling

[0030] (5) An independent peripheral vane locking pin mechanism is provided, with hydraulic transmission or electromagnetic braking to ensure the safety of shutdown

[0031] (6) Solenoid valves are set at the oil ports of the cylinder to ensure the locking function of the cylinder during long - term shutdown such as installation, maintenance, and fixed pitch

[0032] (7) Methods such as super capacitors / peripheral accumulators can be used to realize the emergency feathering function, which is flexible and variable. Brief Description of the Drawings

[0033] Figure 1 is the system schematic diagram of the present invention.

[0034] Figure 2 is the schematic diagram of the principle of the vane locking pin structure of the system of the present invention.

[0035] Figure 3 is the schematic diagram of the principle of the independent cooling system of the system of the present invention.

[0036] Figure 4 is the structure diagram of the preferred embodiment 4 - group cylinder arrangement with blades of the present invention.

[0037] Figure 5 is the structure diagram of the preferred embodiment 2 - group cylinder arrangement with blades of the present invention.

[0038] Figure 6 is the structure diagram of the preferred embodiment 2 - group cylinder arrangement of the present invention.

[0039] Figure 7 is the structure diagram of the preferred embodiment 4 - group cylinder arrangement of the present invention.

[0040] Figure 8 is the structure diagram of the preferred embodiment 4 - group cylinder arrangement of the present invention.

[0041] The markings in the figure are: 1, positive pressure oil replenishing tank; 2(2.1, 2.2), one-way valve; 3, hydraulic pump with two-way servo electric control (four-quadrant power control); 4, solenoid valve; 5(5.1, 5.2), safety overflow valve; 6(6.1, 6.2), pilot-operated check valve; 7(7.1, 7.2), pressure and temperature sensor; 8, vane locking pin system; 9, independent cooling unit; 10(10.1, 10.2, 10.3, 10.4), hydraulic cylinders with equal volume arrangement; 20, servo cylinder; 21, telescopic rod; 30, pitch structure; 31, mounting opening; 32, rotating plate; 33, fixed point; 331, first fixed point; 332, second fixed point. Detailed implementation mode

[0042] First embodiment:

[0043] As Figure 1 shown, an electro-hydraulic servo pitch system for a wind turbine provided by the present invention includes an electro-hydraulic servo system, a servo cylinder 20, and a pitch structure 30;

[0044] The electro-hydraulic servo system has a servo motor and a hydraulic pump 3. The hydraulic pump 3 has a two-way pressure output function, and the servo motor is used to control the delivery of the power oil of the hydraulic pump 3;

[0045] The servo cylinder 20 has a displacement sensor, and the displacement sensor is used to monitor the stroke of the telescopic rod 21 of the servo cylinder 20. The oil chamber cylinder body of the servo cylinder 20 is connected to the hydraulic pump, and the servo cylinders 20 are arranged in an even number of pairs in series;

[0046] As Figures 4 to 8 shown, the pitch structure 30 has a spherical structure. The spherical structure has a mounting opening 31. The mounting opening 31 has a rotating plate 32 and a fixed point 33. The rotating plate 32 is rotatably arranged on the mounting opening 31, and the fixed point 33 is fixedly arranged on the edge of the mounting opening 31.

[0047] Furthermore, a hub 35 is fixedly installed on the mounting opening 31. A blade 36 is installed on the outer edge of the hub 35. The hub 35 is rotatably arranged at the position of the mounting opening 31. The rotating plate 32 is connected to the hub 35. The rotating plate 32 can drive the hub 35 and the blade 36 to rotate. The servo cylinder 20 is located inside the mounting opening 31. In practical applications, the telescopic rod 21 of the servo cylinder 20 drives the rotating plate 32 to rotate, so that the rotating plate 32 drives the hub 35 and the blade 36 to rotate.

[0048] The electro-hydraulic servo system and the servo oil cylinder 20 are arranged on the fixed point 33. The tail of the oil chamber cylinder body of the servo oil cylinder 20 is hinged on the fixed point 33, and the telescopic rod 21 of the servo oil cylinder 20 is hinged on the rotating piece 32.

[0049] Second Embodiment:

[0050] As Figure 4 and Figure 5 shown, the number of the servo oil cylinders 20 in this embodiment is two groups, and these two groups of servo oil cylinders 20 are respectively symmetrically arranged on both sides of the rotating piece 32, that is, the connection points of these two groups of servo oil cylinders 20 on the rotating piece 32 are symmetrically arranged relative to the central position of the rotating piece 32.

[0051] As Figure 6 and Figure 7 shown, the number of the servo oil cylinders 20 is four groups. The servo oil cylinder 20 includes a first servo oil cylinder, a second servo oil cylinder, a third servo oil cylinder and a fourth servo oil cylinder, and the fixed point 33 includes a first fixed point 331 and a second fixed point 332. The first servo oil cylinder and the second servo oil cylinder are arranged on the first fixed point 331, and the third servo oil cylinder and the fourth servo oil cylinder are arranged on the second fixed point 332. The telescopic rods of the first servo oil cylinder and the third servo oil cylinder are hinged at the first position point 333 of the rotating piece 32, and the telescopic rods of the second servo oil cylinder and the fourth servo oil cylinder are hinged at the second position point 334. The first position point 333 and the second position point 334 are symmetrically arranged relative to the central position point of the rotating piece 32, and the stroke controls of the first servo oil cylinder and the third servo oil cylinder are in a mutually exclusive relationship, that is, the telescopic stroke of the telescopic rod of the first servo oil cylinder and the stroke of the telescopic rod of the third servo oil cylinder are opposite; and the stroke controls of the second servo oil cylinder and the fourth servo oil cylinder are in a mutually exclusive relationship; that is, the telescopic stroke of the telescopic rod of the second servo oil cylinder and the stroke of the telescopic rod of the fourth servo oil cylinder are opposite.

[0052] As Figure 3 shown, the present invention also has an externally independent circulating cooling system 9, and the circulating cooling system 9 is matched with a temperature monitoring sensor 7 and a pressure monitoring sensor. The circulating cooling system 9 cools the servo motor and the hydraulic pump or adjusts the pressure according to the heat generation requirement of the electro-hydraulic servo system.

[0053] As Figure 2 shown, the blade of the paddle has a locking pin structure 8, and the locking pin structure 8 is controlled by hydraulic transmission or electromagnetic braking.

[0054] The electro-hydraulic servo system has a safety overflow valve 5 and a replenishing valve, and the replenishing valve is used to realize the functions of compensating oil for insufficient flow and overflowing excess flow.

[0055] It further includes a control unit, which is connected to the displacement sensor. The control unit records the angle of the blade according to the parameters obtained by the displacement sensor, and accordingly controls the servo oil cylinder to achieve constant-volume closed-loop feedback control.

[0056] The implementation method of the electro-hydraulic servo pitch system for a wind turbine provided by the present invention includes the following steps:

[0057] The servo motor drives the hydraulic pump 3 to output a pressure oil source in a bidirectional high-frequency manner, and constitutes the power control unit of the closed system;

[0058] The power oil source enters one side of the hydraulic cylinder 20. The servo oil cylinder 20 records the blade angle through the displacement sensor, and realizes constant-volume closed-loop feedback control when the servo oil cylinder 20 acts;

[0059] The electro-hydraulic servo system is matched with a pressure sensor. According to the feedback of the pressure parameter and the displacement of the servo oil cylinder 20, a closed-loop control adjustment of the blade angle is formed. The forward and reverse actions of the servo motor drive the extension and retraction of the oil cylinder to realize the change of the blade angle.

[0060] The implementation method of the electro-hydraulic servo pitch system for a wind turbine provided by the present invention includes the following steps: limiting the bidirectional pressure through a safety relief valve, and realizing the functions of underflow oil replenishment and overflow of excess flow through an oil replenishing valve.

[0061] The beneficial effects of the present invention are as follows: an electro-hydraulic servo pitch solution is provided, which maintains the characteristics of flexible servo electric action control and small volume, and introduces a closed hydraulic system, eliminating the oil source pumping station and having extremely few pipeline components, thereby bringing extremely low leakage points, saving installation space and having a great cost advantage. At the same time, an equal-volume servo oil cylinder scheme is adopted, with small heat loss, low noise, and a compact structure, retaining the advantages of high hydraulic transmission efficiency, shock absorption and energy absorption, and extending the service life of structural components such as blades. The present invention also matches high-performance blade locks, emergency feathering, efficient heat dissipation and other systems to ensure the safety and reliability of the system.

[0062] An electro-hydraulic servo pitch system for a wind turbine and its implementation method provided by the present invention include a complete set of servo electro-hydraulic control systems and pitch drive solutions, and the characteristics are as follows:

[0063] (1) An electro-hydraulic servo system is adopted, and the servo motor and the hydraulic pump cooperate to realize the output of a bidirectional pressure oil source with steplessly adjustable flow rate, constituting a servo hydraulic closed-loop system; the system can realize the four-quadrant high-frequency output of power.

[0064] (2) The pitch drive device is a uniquely designed low-fluid-resistance servo oil cylinder, including precise displacement sensor feedback.

[0065] (3) The oil cylinders are arranged in a way that the oil cylinders face each other (the rodless cavity of one oil cylinder is connected in series with the rod cavity of another oil cylinder), achieving an equal-volume arrangement of the system's flow rate, thereby reducing the problems of large oil replenishment volume and high heat generation in the closed system caused by the volume difference. The arrangement of the oil cylinders is not limited to 2 pairs. Even-numbered arrangements such as 4 pairs can also be achieved. For the arrangement method of 2 pairs, please refer to Figure 5 and Figure 6 's solution. For the solution of 4 pairs of arrangements, please refer to Figure 4 , Figure 7 and Figure 8 's solution; It is also possible to directly use equal-volume double-rod oil cylinders for arrangement to achieve an equal-volume closed-loop circuit;

[0066] (4) A unique small-volume, low-pressure pressurized oil tank is used for oil replenishment in the closed system;

[0067] An independent external circulating cooling system is provided, and the system is matched with temperature monitoring. According to the heat generation of the system, the pump and motor are cooled; it is not limited to forms such as air cooling and liquid cooling

[0068] (5) An independent external vane locking pin mechanism is provided, with hydraulic transmission or electromagnetic braking to ensure the safety of shutdown

[0069] (6) Solenoid valves are installed at the oil ports of the oil cylinders to ensure the locking function of the oil cylinders during long-term shutdowns such as installation, maintenance, and fixed pitch

[0070] (7) Methods such as supercapacitors / external energy accumulators can be used to achieve the emergency feathering function, which is flexible and variable.

[0071] In a further preferred embodiment, a bottle body is provided inside the spherical structure of the variable pitch structure 30. A lubricating liquid is contained in the bottle body. The lubricating liquid is conveyed through a feeding pump and a delivery pipe, and the port of the delivery pipe is aligned with the liquid adding position at the mounting opening. Additionally, one end of the rotating piece has a sponge structure. When the sponge structure rotates to the liquid adding position, a signal is generated through induction by a sensor, enabling the control system to know that the sponge structure is at this position, or the control system itself knows the rotation angle of the rotating piece. When the sponge structure rotates to the liquid adding position, it can be known that it has rotated to a specific position. Then, the feeding pump is started to convey the lubricating liquid through the delivery pipe and spray it onto the sponge structure. The sponge structure absorbs the liquid. When the rotating piece rotates, the liquid contaminated by the sponge structure is used to lubricate the position of the rotation track relied on by the rotating piece, making the rotation of the rotating piece smoother, so as to achieve the daily maintenance of the rotating piece and the contact track of the rotating piece. And this lubrication process can be maintained once every few months. This process utilizes the advantage that the rotating piece can rotate. Additionally, a nozzle can be provided at the end of the delivery pipe, and the delivery pipe is arranged in the internal space of the spherical structure, while the nozzle faces the liquid adding position at the mounting opening so that the delivery pipe does not affect the rotation of the rotating piece. Preferably, the sponge structure is arranged at the end position of the rotating piece, and the outer end of the sponge structure abuts against the track structure to achieve the maintenance of the track.

[0072] In another embodiment, the mounting opening has a mounting hole, and the mounting holes between two adjacent mounting openings are connected. In particular, the mounting hole at the liquid adding position can be connected to the mounting hole of another mounting opening, and a second sponge structure is arranged inside the connected space. The two ends of the second sponge structure are respectively located at the tails of the mounting holes, that is, the ends of the second sponge structure slightly protrude into the external space of the mounting holes. When the rotating piece rotates, the first sponge structure on the rotating piece will be contaminated by the second sponge structure inside the space, thus realizing liquid transfer, and thus realizing the liquid supplement for the sponge structures on the rotating pieces of other surrounding mounting openings. In this way, it is not necessary to supplement the liquid at three positions simultaneously.

[0073] In a further preferred implementation process, that is, lubricating liquid is supplemented to the first sponge structure of the rotating pieces in the first group, and then when the rotating pieces rotate, the first group of tracks are lubricated and maintained through the first sponge structure. When the first sponge structure touches the second sponge structure, the liquid is supplemented to the second sponge structure, and the second sponge structure is transferred to the other end through the space inside, and the first sponge structure of the mounting opening in the second group is supplemented with liquid, thereby realizing the maintenance of the tracks of the mounting opening in the second group.

Claims

1. An electro-hydraulic servo pitch system for a wind turbine generator set, characterized in that, Including: An electro-hydraulic servo system, having a servo motor and a hydraulic pump, the hydraulic pump having a two-way pressure output function, and the servo motor being used to control the delivery of power oil of the hydraulic pump; A servo cylinder, having a displacement sensor, the displacement sensor being used to monitor the stroke of the telescopic rod of the servo cylinder, the oil chamber cylinder body of the servo cylinder being connected to the hydraulic pump, and the servo cylinders being arranged in an even number of pairs in series facing each other; A pitch-changing structure, having a spherical structure, the spherical structure having a mounting opening, the mounting opening having a rotating piece and a fixed point, the rotating piece being rotatably arranged on the mounting opening, the fixed point being fixedly arranged at the edge of the mounting opening, the rotating piece being connected to the blade, the electro-hydraulic servo system and the servo cylinder being arranged on the fixed point, the tail of the oil chamber cylinder body of the servo cylinder being hinged to the fixed point, and the telescopic rod of the servo cylinder being hinged to the rotating piece; Inside the spherical structure of the pitch-changing structure, there is a bottle body, and inside the bottle body, there is a lubricating liquid. The lubricating liquid is transported through a feeding pump and a delivery pipe, and the port of the delivery pipe is aligned with the liquid adding level point of the mounting opening; One end of one side of the rotating piece has a first sponge structure, the mounting opening has a mounting hole, and the mounting holes between two adjacent mounting openings are connected. A second sponge structure is arranged inside the connected space, and both ends of the second sponge structure are respectively located at the tail of the mounting hole; 2. The electro-hydraulic servo pitch system for a wind turbine according to claim 1, characterized in that A hub is fixedly mounted on the mounting opening, blades are mounted on the outer edge of the hub, the hub is rotatably arranged at the position of the mounting opening, the rotating piece is connected to the hub, and the rotating piece can drive the hub and the blades to rotate; The number of the servo cylinders is two groups, and these two groups of servo cylinders are respectively symmetrically arranged on both sides of the rotating piece, that is, the connection points of these two groups of servo cylinders on the rotating piece are symmetrically arranged relative to the central position of the rotating piece; 3. The electro-hydraulic servo pitch system for a wind turbine according to claim 1, characterized in that, The number of the servo cylinders is four groups. The servo cylinders include a first servo cylinder, a second servo cylinder, a third servo cylinder, and a fourth servo cylinder, and the fixed points include a first fixed point and a second fixed point. The first servo cylinder and the second servo cylinder are arranged on the first fixed point, the third servo cylinder and the fourth servo cylinder are arranged on the second fixed point. The telescopic rods of the first servo cylinder and the third servo cylinder are hinged to the first position point of the rotating piece, the telescopic rods of the second servo cylinder and the fourth servo cylinder are hinged to the second position point, the first position point and the second position point are symmetrically arranged relative to the central position point of the rotating piece, and the stroke controls of the first servo cylinder and the third servo cylinder are in a relationship of opposite repulsion, while the stroke controls of the second servo cylinder and the fourth servo cylinder are in a relationship of opposite repulsion; 4. The electro-hydraulic servo pitch system for a wind turbine according to claim 1, characterized in that, There is also an externally independent circulating cooling system, and the circulating cooling system is matched with a temperature monitoring sensor. The circulating cooling system cools the servo motor and the hydraulic pump according to the heat generation requirement of the electro-hydraulic servo system; 5. The electro-hydraulic servo pitch system for a wind turbine according to claim 1, characterized in that, The blade of the blade has a locking pin structure, and the locking pin structure is controlled by hydraulic transmission or electromagnetic braking.

6. The electro-hydraulic servo pitch system for a wind turbine according to claim 1, characterized in that, The electro-hydraulic servo system is equipped with a safety overflow valve and a fluid replenishing valve, and the fluid replenishing valve is used to achieve the functions of under-flow oil replenishment and overflow of excess flow.

7. The electro-hydraulic servo pitch system for a wind turbine according to claim 1, characterized in that, It further includes a control unit, which is connected to the displacement sensor. The control unit records the angle of the blade according to the parameters obtained by the displacement sensor, and accordingly controls the servo cylinder to achieve constant-volume closed-loop feedback control.

8. The implementation method of the electro-hydraulic servo pitch system for a wind turbine according to claim 1, characterized in that It includes the following steps: The servo motor drives the hydraulic pump to output a pressure oil source in a bidirectional high-frequency manner, and constitutes the power control unit of the closed-loop system; The power oil source enters one side of the hydraulic cylinder. The servo cylinder records the blade angle through the displacement sensor, and realizes constant-volume closed-loop feedback control when the servo cylinder acts; The electro-hydraulic servo system is matched with a pressure sensor. According to the feedback of the pressure parameters and the displacement of the servo cylinder, a closed-loop control adjustment of the blade angle is constituted. The forward and reverse actions of the servo motor drive the extension and retraction of the cylinder to realize the change of the blade angle.

9. The implementation method of the electro-hydraulic servo pitch system for a wind turbine according to claim 8, wherein It includes the following steps: limiting the bidirectional pressure through the safety overflow valve, and realizing the functions of under-flow oil replenishment and overflow of excess flow through the fluid replenishing valve.

Images