Digital control motor-driven high-response pump-controlled pitch system

Abstract

The present invention provides a digitally controlled motor-driven high-response pump-controlled pitch system, comprising: a variable-displacement hydraulic cylinder, a hydraulic pump and an accumulator bank. The variable-displacement hydraulic cylinder has a first chamber, a second chamber, a third chamber and a fourth chamber. The second chamber and the fourth chamber are connected in parallel and then connected to an oil port of the hydraulic pump through a second solenoid valve. The third chamber is connected to another oil port of the hydraulic pump through a first solenoid valve. The first chamber is connected to the accumulator bank through a fourth solenoid valve. In the digitally controlled motor-driven high-response pump-controlled pitch system of the present invention, a variable-displacement hydraulic cylinder with four working chambers is adopted, and a closed-loop control system is formed by different combinations of the working chambers, removing the hydraulic oil tank which accounts for 70-85% of the volume and mass in the hydraulic system, and reducing the application cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and particularly relates to a digitally controlled motor-driven high-response pump-controlled pitch system. Background Art

[0002] Grid-connected wind turbines convert the kinetic energy of the wind into mechanical energy, and then convert the mechanical energy into electrical energy and connect it to the grid. Since the wind speed changes at any time, the wind turbines operating in the wild for a long time are subjected to very complex and harsh alternating loads.

[0003] The impeller is a key component for capturing wind energy. The impeller is composed of blades and a hub. The blades have an aerodynamic shape and generate a torque under the action of the air flow to drive the impeller to rotate. The torque is transmitted to the gearbox through the hub and the main shaft for speed increase to drive the generator, and then the voltage is converted by the converter to be completely consistent with the grid voltage frequency, amplitude, and phase, and then connected to the grid through the box transformer, thus completing the energy conversion. The pitch control system can obtain more wind energy by controlling the windward angle of the blades and reduce the load caused by gusts, so it has been widely used.

[0004] Generally, below the rated wind speed, the starting pitch angle of the blade is about 87°. When the wind turbine starts, the pitch angle gradually rotates towards the 0° direction. At this time, the lifting force generated by the air flow on the hub gradually increases, and the impeller rotates faster and faster. When the rated speed is reached, the wind turbine is connected to the grid for operation. Therefore, controlling the pitch angle of the blade is the key to the pitch control system.

[0005] The pitch system is divided into two categories: hydraulic pitch system and electric pitch system. Among them, the hydraulic system occupies less space, and the hub and bearings are relatively small. There is no need to lubricate the gears, reducing the centralized lubrication points. The electric pitch system occupies a large space and requires lubrication of the bearings.

[0006] In the prior art, such as the Chinese patent application document with the publication number CN101624970, it discloses a hydraulic pitch system for wind power generation equipment; and the Chinese patent document with the authorization announcement number CN109441724B discloses a safety throttling device for a hydraulic pitch system. In the above two prior arts, the pitch system is supplied with oil through an oil tank, and the volume and mass of the oil tank are relatively large, and the application cost is relatively high.

[0007] Therefore, it is necessary to design a digitally controlled motor-driven high-response pump-controlled pitch system with a simple structure, reduced application cost, and reduced risk of external leakage of the system to solve the current technical problems. Summary of the Invention

[0008] In view of the deficiencies existing in the prior art, the present invention provides a digital control motor-driven high-response pump-controlled pitch system with a simple structure, reduced application costs, and reduced risk of external leakage of the system.

[0009] The technical solution of the present invention is as follows: A digital control motor-driven high-response pump-controlled pitch system includes: a variable displacement hydraulic cylinder, a hydraulic pump, and an accumulator group; the variable displacement hydraulic cylinder has an outer cylinder body, an inner tube fixed inside the outer cylinder body, and a piston tube slidably disposed outside the inner tube. The rodless chamber between the outer cylinder body and the piston tube is the first chamber, the rod chamber between the outer cylinder body and the piston tube is the second chamber, the rodless chamber between the piston tube and the inner tube is the third chamber, and the rod chamber between the piston tube and the inner tube is the fourth chamber; the second chamber and the fourth chamber are connected in parallel and then connected to an oil port of the hydraulic pump through a second solenoid valve, the third chamber is connected to the other oil port of the hydraulic pump through a first solenoid valve, and the first chamber is connected to the accumulator group through a fourth solenoid valve.

[0010] The accumulator group is connected to the first chamber through a logic control valve, and the second chamber and the fourth chamber are connected in parallel and then connected to the third chamber through a fifth solenoid valve.

[0011] A first throttle valve is connected between the logic control valve and the first chamber, and a third check valve is connected between the first throttle valve and the first chamber.

[0012] A pressure control sequence valve is connected between the fifth solenoid valve and the third chamber.

[0013] The accumulator group has a high-pressure accumulator and a low-pressure accumulator. The low-pressure accumulator is connected to an oil port of the hydraulic pump through a second throttle valve, and the other oil port of the hydraulic pump is connected to the high-pressure accumulator through a third solenoid valve.

[0014] A first overflow valve is connected to the third chamber. A first check valve and a second check valve are connected in parallel to the first overflow valve; a third overflow valve and a sixth solenoid valve are connected in parallel to the first check valve, and the third overflow valve and the sixth solenoid valve are connected in parallel and then connected to the first overflow valve; a fourth overflow valve and a seventh solenoid valve are connected in parallel to the second check valve, and the fourth overflow valve and the seventh solenoid valve are connected in parallel and then connected to the first overflow valve.

[0015] A first heat exchanger, a second hydraulic control check valve, and a second one-way throttle valve are sequentially connected between the hydraulic pump and the second solenoid valve.

[0016] A first one-way throttle valve, a first hydraulic control check valve, and a second heat exchanger are sequentially connected between the first solenoid valve and the hydraulic pump.

[0017] The hydraulic pump is a four-quadrant hydraulic pump driven by a control motor.

[0018] A displacement sensor for detecting the position of the piston tube is provided on the variable volume hydraulic cylinder.

[0019] Advantages of the present invention:

[0020] (1) In the digital control motor-driven high-response pump-controlled pitch system of the present invention, a variable volume hydraulic cylinder with four working chambers is adopted, and a closed-loop control system is formed by different combinations of working chambers, removing the hydraulic oil tank that accounts for 70-85% of the volume and mass in the hydraulic system, reducing the application cost;

[0021] (2) The variable volume hydraulic cylinder is connected to the hydraulic pump through valve parts, with a simple structure. There is no need for an actuator and a middle rotating device and distributor for the oil pressure source, greatly reducing the risk of external leakage in the hydraulic system, and reducing the harm that the system stability and robustness deteriorate due to leakage, resulting in an increase in the path position and path tracking error of the pitch-controlled wind turbine and even pitch failure;

[0022] (3) In an emergency, the high-pressure accumulator quickly and directly fills the variable volume hydraulic cylinder with oil to complete a quick feathering response. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the digital control motor-driven high-response pump-controlled pitch system in the present invention.

[0024] Figure 2 It is a schematic structural diagram of the variable volume hydraulic cylinder in the present invention. Detailed Embodiments

[0025] Now, various exemplary embodiments of the present invention will be described in detail with reference to the drawings. The description of the exemplary embodiments is merely illustrative and in no way limits the present invention and its application or use. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present invention thorough and complete, and to fully convey the scope of the present invention to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, the components of materials, numerical expressions and values set forth in these embodiments should be construed as merely exemplary and not as limitations.

[0026] In the present invention, words such as "first", "second" and similar words do not denote any order, quantity or importance, but are only used to distinguish different parts. Words such as "comprising" or "including" mean that the elements before the word cover the elements listed after the word, and do not exclude the possibility of also covering other elements. "Upper", "lower", "left", "right", etc. are only used to represent relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0027] As Figure 1 shown, the digital control motor-driven high-response pump-controlled pitch system includes: a variable displacement hydraulic cylinder 24, a hydraulic pump 14.1 and an accumulator bank; the variable displacement hydraulic cylinder 24 has an outer cylinder body 241, an inner tube fixed inside the outer cylinder body 241, and a piston tube 242 slidably disposed outside the inner tube 243. The rodless chamber between the outer cylinder body 241 and the piston tube 242 is the first chamber A, the rod chamber between the outer cylinder body 241 and the piston tube 242 is the second chamber B, the rodless chamber between the piston tube 242 and the inner tube 243 is the third chamber C, and the rod chamber between the piston tube 242 and the inner tube 243 is the fourth chamber D. Pumping hydraulic oil into the first chamber A and the third chamber C respectively can drive the piston tube 242 to extend outwards from the outer cylinder body 241, and pumping hydraulic oil into the second chamber B and the fourth chamber D respectively can drive the piston tube 242 to retract into the outer cylinder body 241; the second chamber B and the fourth chamber D are connected in parallel and then connected to an oil port S of the hydraulic pump 14.1 through a second solenoid valve 2.2, the third chamber is connected to another oil port P of the hydraulic pump 14.1 through a first solenoid valve 2.1, and the first chamber A is connected to the accumulator bank through a fourth solenoid valve 2.4.

[0028] In the above embodiment, when the pitch opening action is implemented, the variable displacement hydraulic cylinder 24 drives the blade to pitch in the -5° direction. The first solenoid valve 2.1 and the second solenoid valve 2.2 are energized. The pressure oil flows into the second chamber B and the fourth chamber D through the oil port S of the hydraulic pump 14.1 and the second solenoid valve 2.2, driving the piston tube 242 to retract, and then driving the blade to rotate in the -5° direction. At the same time, the hydraulic oil in the third chamber C flows to the oil port P of the hydraulic pump 14.1 through the first solenoid valve 2.1, and the hydraulic oil in the first chamber A returns to the accumulator bank through the fourth solenoid valve 2.4; when the pitch closing action is implemented, the variable displacement hydraulic cylinder 24 drives the blade to pitch in the 87° direction. The first solenoid valve 2.1 and the second solenoid valve 2.2 are energized. The pressure oil flows into the third chamber C through the oil port P of the hydraulic pump 14.1 and the first solenoid valve 2.1, driving the piston tube 242 to extend, and then driving the blade to rotate in the 87° direction. The hydraulic oil in the second chamber B and the fourth chamber D flows to the oil port S of the hydraulic pump 14.1 through the second solenoid valve 2.2, and the hydraulic oil in the accumulator bank enters the first chamber A through the fourth solenoid valve 2.4.

[0029] In some embodiments, the accumulator bank is connected to the first chamber A through a logic control valve 27.1. The second chamber B and the fourth chamber D are connected in parallel and then connected to the third chamber C through a fifth solenoid valve 8.1. A first throttle valve 6.1 is connected between the logic control valve 27.1 and the first chamber, and a third check valve 3.1 is connected between the first throttle valve 6.1 and the first chamber. A pressure control sequence valve 5.1 is connected between the fifth solenoid valve 8.1 and the third chamber. When the machine stops, the pressurized oil in the accumulator bank enters the inside of the first chamber A through the logic control valve 27.1, the first throttle valve 6.1, and the third check valve 3.1, pushing the piston tube 242 of the variable volume hydraulic cylinder 24 to extend and pushing the blades to feather. The hydraulic oil inside the second chamber B and the fourth chamber D enters the inside of the third chamber C through the fifth solenoid valve 8.1 and the pressure control sequence valve 5.1. The accumulator bank internally has a first accumulator 19.1 and a second accumulator 19.2. The first accumulator 19.1 and the outlet of the pressure control sequence valve 5.1 are used to absorb pressure spikes, and the second accumulator 19.2 is connected to the control oil circuit of the third chamber C to prevent pressure pulsation.

[0030] During the shutdown process, the hydraulic pump 14.1 automatically starts and stops according to the pressure of the first chamber A. When the hydraulic pump 14.1 starts, the pressurized oil passes through the low-pressure accumulator 18, the second throttle valve 7.1, and the fourth hydraulic control check valve 11.4 and enters the oil port S of the hydraulic pump 14.1, then flows out from the oil port P of the hydraulic pump 14.1, and replenishes oil to the high-pressure accumulator 17 through the first hydraulic control check valve 11.1 and the third solenoid valve 2.3. The hydraulic oil reaches the first chamber A through the logic control valve 27.1, the first throttle valve 6.1, and the third check valve 3.1 to complete feathering.

[0031] When an emergency feathering action needs to be performed, all solenoid valves are de-energized, and the hydraulic pump 14.1 immediately stops running. During emergency feathering, the high-pressure accumulator 18 directly supplies oil to the first chamber A. In an emergency, the high-pressure accumulator 18 quickly and directly fills the variable volume hydraulic cylinder 24 with oil to complete a fast feathering response. The emergency feathering speed is determined by the first throttle valve 6.1 and the pressure control sequence valve 5.1. The decrease in the accumulator pressure causes the control pressure of the pressure control sequence valve 5.1 to gradually decrease, thereby gradually closing the pressure control sequence valve 5.1 to prevent over-speed pitching.

[0032] In some embodiments, the accumulator bank includes a high-pressure accumulator 17 and a low-pressure accumulator 18. The low-pressure accumulator 18 is connected to an oil port S of the hydraulic pump 14.1 via a second throttle valve 7.1. Another oil port P of the hydraulic pump 14.1 is connected to the high-pressure accumulator 17 via a third solenoid valve 2.3. As an implementation of pressurizing the high-pressure accumulator 17, the hydraulic pump 14.1 is started to drive hydraulic oil to flow from the low-pressure accumulator 18, the throttle valve 7.1, the fourth hydraulic check valve 11.4 to the oil port S of the hydraulic pump 14.1, and then flow out from the oil port P of the hydraulic pump 14.1, pass through the first hydraulic check valve 11.1 and the third solenoid valve 2.3 to enter the high-pressure accumulator 17. After the pressure of the high-pressure accumulator 17 reaches the set value, the pressurization stops.

[0033] In some embodiments, a first relief valve 9.1 is connected to the third chamber C. A first check valve 10.1 and a second check valve 10.2 are connected in parallel to the first relief valve 9.1. A third relief valve 9.3 and a sixth solenoid valve 31.1 are connected in parallel to the first check valve 10.1. After being connected in parallel, the third relief valve 9.3 and the sixth solenoid valve 31.1 are connected to the first relief valve 9.1. A fourth relief valve 9.4 and a seventh solenoid valve 31.2 are connected in parallel to the second check valve 10.2. After being connected in parallel, the fourth relief valve 9.4 and the seventh solenoid valve 31.2 are connected to the first relief valve 9.1. In order to prevent the hydraulic oil inside the variable-displacement hydraulic cylinder 24 from spraying out and polluting the environment during maintenance, before maintenance, it is necessary to energize the sixth solenoid valve 31.1, the seventh solenoid valve 31.2 and the fourth solenoid valve 2.4 to relieve the pressure of the first chamber A, the second chamber B, the third chamber C and the fourth chamber D of the variable-displacement hydraulic cylinder 24, preventing high-pressure spraying during maintenance from polluting the environment.

[0034] In some embodiments, a first heat exchanger 13.1, a second hydraulic check valve 11.2 and a second one-way throttle valve 4.2 are sequentially connected between the hydraulic pump 14.1 and the second solenoid valve 2.2. A second relief valve 9.2 is connected between the second hydraulic check valve 11.2 and the second one-way throttle valve 4.2. The other end of the second relief valve 9.2 is respectively connected to the first check valve 10.1 and the second check valve 10.2.

[0035] In some embodiments, a first one-way throttle valve 4.1, a first hydraulic check valve 11.1 and a second heat exchanger 13.2 are sequentially connected between the first solenoid valve 2.1 and the hydraulic pump 14.1.

[0036] In some embodiments, the hydraulic pump 14.1 is a four-quadrant hydraulic pump driven by a control motor 16.1. The control motor 16.1 drives the four-quadrant hydraulic pump to drive the variable-displacement hydraulic cylinder to complete the pitch action of the wind turbine, with fast response, reliable control and simple operation.

[0037] In some embodiments, a displacement sensor 31.1 for detecting the position of the piston tube 242 is provided on the variable volume hydraulic cylinder 24. During the process of pitching the blades open and closed, the displacement sensor 31.1 periodically detects the actual position of the piston tube 242 and transmits the detected signal to the controller system for corresponding comparison, so as to verify whether the actual pitch angle of the wind turbine is consistent with the set angle.

[0038] So far, the embodiments of the present invention have been described in detail. In order to avoid obscuring the concept of the present invention, some details well known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0039] The above-described embodiments only represent some embodiments of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent shall be subject to the appended claims.

Claims

1. A digital control motor-driven high-response pump-controlled pitch system, characterized in that, Comprising: A variable displacement hydraulic cylinder, a hydraulic pump and an accumulator group; The variable displacement hydraulic cylinder has an outer cylinder body, an inner tube fixed inside the outer cylinder body, and a piston tube slidably disposed outside the inner tube. The rodless cavity between the outer cylinder body and the piston tube is the first chamber, the rod chamber between the outer cylinder body and the piston tube is the second chamber, the rodless cavity between the piston tube and the inner tube is the third chamber, and the rod chamber between the piston tube and the inner tube is the fourth chamber; The second chamber and the fourth chamber are connected in parallel and then connected to an oil port of the hydraulic pump through a second solenoid valve. The third chamber is connected to the other oil port of the hydraulic pump through a first solenoid valve. The first chamber is connected to the accumulator group through a fourth solenoid valve; The accumulator group is connected to the first chamber through a logic control valve. The second chamber and the fourth chamber are connected in parallel and then connected to the third chamber through a fifth solenoid valve; A first throttle valve is connected between the logic control valve and the first chamber, and a third check valve is connected between the first throttle valve and the first chamber; A pressure control sequence valve is connected between the fifth solenoid valve and the third chamber.

2. The digital control motor-driven high-response pump-controlled pitch system according to claim 1, characterized in that: The accumulator group has a high-pressure accumulator and a low-pressure accumulator. The low-pressure accumulator is connected to an oil port of the hydraulic pump through a second throttle valve. The other oil port of the hydraulic pump is connected to the high-pressure accumulator through a third solenoid valve.

3. The digital control motor-driven high-response pump-controlled pitch system according to claim 1, characterized in that: A first relief valve is connected to the third chamber. A first check valve and a second check valve are connected in parallel to the first relief valve; A third relief valve and a sixth solenoid valve are connected in parallel to the first check valve, and the third relief valve and the sixth solenoid valve are connected in parallel and then connected to the first relief valve; A fourth relief valve and a seventh solenoid valve are connected in parallel to the second check valve, and the fourth relief valve and the seventh solenoid valve are connected in parallel and then connected to the first relief valve.

4. The digital control motor-driven high-response pump-controlled variable pitch system according to claim 1, wherein: A first heat exchanger, a second hydraulic control check valve and a second one-way throttle valve are sequentially connected between the hydraulic pump and the second solenoid valve.

5. The digital control motor-driven high-response pump-controlled pitch system according to claim 1, characterized in that: A first one-way throttle valve, a first hydraulic control check valve and a second heat exchanger are sequentially connected between the first solenoid valve and the hydraulic pump.

6. The digital control motor-driven high-response pump-controlled variable pitch system according to claim 1, wherein: The hydraulic pump is a four-quadrant hydraulic pump driven by a control motor.

7. The digital control motor-driven high-response pump-controlled pitch system according to claim 1, characterized in that: A displacement sensor for detecting the position of the piston tube is provided on the variable displacement hydraulic cylinder.

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