Pitch cooperative control method and system of double eha-driven independent variable pitch system

Abstract

The present application relates to a kind of variable pitch collaborative control methods of double EHA drive independent variable pitch system, it includes the following steps, step 1: based on wind farm SCADA and wind turbine data, variable pitch system load and unit power prediction model are established;Step 2: using variable pitch load and unit power prediction model, obtain unit variable pitch load and unit power prediction value;Step 3: according to pitch angle instruction and variable pitch load prediction value, the control link of first drive unit is established;Step 4: according to variable pitch load prediction value and the speed error feedback signal of first drive unit, the control link of second drive unit is established;Step 5: the first drive unit and second drive unit are cooperatively controlled, the collaborative control of double drive unit is realized.The present application receives pitch controller master control system pitch instruction, controls two sets of drive unit to carry out position and pressure control respectively, realizes the high-precision, high dynamic tracking of double drive independent variable pitch system to master control system pitch angle instruction.

Description

Technical Field

[0001] This application relates to the field of wind power generation technology, specifically to a pitch coordination control method and system for a dual EHA-driven independent pitch system. Background Technology

[0002] The pitch control system of a wind turbine is the core system for the safe, stable, and efficient operation of the turbine. However, pitch control systems suffer from high failure rates and high maintenance costs. Furthermore, the increasing size of wind turbines and the continuous development of offshore wind power place higher demands on pitch control systems in terms of stability, reliability, and efficiency.

[0003] The increasing size of wind turbine units leads to greater loads on pitch control systems. Single-drive pitch control systems, due to their limited driving force, can no longer meet the requirements of pitch drive systems. In addition, single-drive pitch control systems suffer from radial off-center loading and excessive local loads. Therefore, there is an urgent need to design a more reliable pitch control system that is more suitable for large-capacity units. Among them, dual (multi)-drive pitch control systems are an effective solution.

[0004] In a prior art document titled "A Direct-Drive Hydraulic Pitch Control Mechanism for Wind Turbine Generators," the pitch mechanism is driven by two closed-loop pump-controlled hydraulic systems. When the hydraulic circuit of one pitch drive system fails and loses pressure, the control system automatically switches to the hydraulic circuit of the second drive system, achieving a redundant design for the pitch system and improving system reliability. However, this system uses a single hydraulic cylinder to achieve pitch control, still exhibiting problems such as radial off-center loading and excessive local loads. In another prior art document titled "A Dual-Motor Pitch Control System for Wind Turbine Generators," dual-drive control can evenly distribute the load, resulting in a smaller output from a single drive, thereby reducing the fatigue load on the bearing teeth, extending the life of the pitch bearings, and achieving synchronous control of the two motors. Furthermore, in a prior art document titled "A Control Method and Device for a Dual-Motor Pitch System," the master motor and slave motor are controlled separately, with part of the target torque output from the master motor and the other part from the slave motor, achieving coordinated control of the master and slave motors to ensure the blades reach the target position. As can be seen from the information disclosed in the above documents, electric pitch technology is relatively mature. However, how to better combine the advantages of hydraulic systems with large pitch systems still needs further exploration. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention receives pitch commands from the main control system through a pitch controller and controls two sets of EHA (closed-loop pump-controlled hydraulic system) drive units to perform position and pressure control respectively, thereby achieving high-precision and high-dynamic tracking of the pitch angle commands from the main control system by the dual EHA-driven independent pitch system.

[0006] To achieve the above objectives, the solution adopted by this invention is: a pitch coordination control method for a dual EHA-driven independent pitch system, comprising the following steps:

[0007] Step 1: Based on the wind farm SCADA (Supervisory and Data Acquisition System) and wind turbine data, establish a prediction model for the pitch system load and turbine power.

[0008] Long-term SCADA data and wind turbine data of the wind farm are acquired, the data is cleaned, and normalized to obtain the normalized result x of the state variables and the normalized result y of the actual variables. The normalized result x = {v, w, θ, β, Δψ} of the state variables is used as the input of the neural network, and the normalized result y = {P, T} of the actual variables is used as the input of the neural network. Z As the output of the neural network, the pitch system load and unit power prediction model is trained using an artificial neural network, resulting in the pitch system load and unit power prediction model, as shown below:

[0009]

[0010] In the formula: T Z The actual value of pitch load is represented by f1; the actual value of generator power is represented by P; x = {v, w, θ, β, Δψ} represents the normalized result of the state variables; v represents the wind speed in the rotor plane; w represents the rotor speed; θ represents the blade azimuth angle; β represents the blade pitch angle; Δψ represents the yaw angle error; f1 represents the neural network model of pitch load; f2 represents the neural network model of generator power.

[0011] Step 2: Use the pitch load and unit power prediction model to obtain the predicted values ​​of the pitch load and unit power of the unit;

[0012] The unit's main control system monitors and collects the state variables x = {v, w, θ, β, Δψ} in real time; substituting the normalized state variables into the unit's pitch load model and power prediction model, the predicted values ​​of the unit's pitch load and power are obtained as T. Znorm P norm Then, inverse normalization is performed, as shown in the following process:

[0013]

[0014] In the formula: y represents the normalized result of the actual quantity; y norm This represents the predicted pitch load of the generator unit; y max This represents the predicted power output of the generating unit; y min This represents the minimum value of the actual quantity;

[0015] Step 3: Establish the control loop of the first EHA drive unit based on the pitch angle command and the predicted pitch load value;

[0016] The pitch angle command signal is converted into a displacement signal for the first hydraulic cylinder, which controls the displacement of the hydraulic cylinder piston rod in the pitch control system. The calculation model for the displacement command signal of the first hydraulic cylinder is as follows:

[0017]

[0018] In the formula: l in This indicates the displacement command signal for the first hydraulic cylinder; R represents the rotation radius of the piston rod end of the first hydraulic cylinder; H represents the distance from the mounting hinge of the first hydraulic cylinder to the center of the blade; α represents the angle between the rotation radius of the piston rod end of the first hydraulic cylinder and the line connecting the mounting hinge of the first hydraulic cylinder to the center of the blade at the 0° pitch angle position; L min This indicates the distance from the end of the piston rod to the hinge position of the first hydraulic cylinder when the pitch angle is 0°.

[0019] The pitch controller will transmit the pitch angle command β from the main control system. in The displacement command signal l of the first hydraulic cylinder is converted into in The control loop of the first EHA drive unit is designed to realize the motion control of the first hydraulic cylinder;

[0020] Step 4: Based on the predicted pitch load value and the speed error feedback signal of the first EHA drive unit, establish the control loop of the second EHA drive unit;

[0021] The pitch controller will predict the pitch load T. Znorm Converted into the second hydraulic cylinder driving force command F in The relationship between the two is as follows:

[0022]

[0023] In the formula: F in Indicates the driving force command parameter for the second hydraulic cylinder; T Znorm This represents the predicted pitch load of the generator unit;

[0024] Step 5: Coordinate the control of the first EHA drive unit and the second EHA drive unit to achieve coordinated control of the two EHA drive units;

[0025] The first EHA drive unit and the second EHA drive unit mentioned in steps 3 and 4 work together to drive the blade pitch, thereby realizing the dynamic high-precision tracking of the pitch angle command of the main control system by the dual EHA drive independent pitch system, and finally realizing the coordinated control of the dual EHA drive units.

[0026] Preferably, step 1 involves acquiring long-term SCADA data and wind turbine data from the wind farm, cleaning the data, and performing normalization processing, specifically as follows:

[0027] The long-term SCADA data and wind turbine data of the wind farm cover all wind conditions. in ≤v≤v out The running status data, v in Indicates the cut-in wind speed, v out Indicates the cut-out wind speed;

[0028] The data cleaning process involves removing data from units that are out of service, data with sensor errors, and data that is subject to interference.

[0029] Acquire long-term SCADA data and wind turbine data from the wind farm, clean the data, and perform normalization processing. The processing steps are as follows:

[0030]

[0031] In the formula: x norm This represents the normalization result of the state variable; x s The input value of the state variable; x min Represents the minimum value of the state variable; x max y represents the maximum value of the state variable; y represents the input value of the actual variable; y norm This represents the normalized result of the actual quantity; y max This represents the maximum value of the actual quantity; x = {v, w, θ, β, Δψ} includes the wind speed in the wind turbine plane v, the wind turbine rotation speed w, the blade azimuth angle θ, the blade pitch angle β, and the yaw angle error Δψ.

[0032] Preferably, the control loop for the first EHA drive unit in step 3, based on the pitch angle command and the predicted pitch load value, is as follows:

[0033] The feedforward control loop C2(s) is designed to implement the displacement command of the first hydraulic cylinder. in Rapid tracking; the displacement command signal of the first hydraulic cylinder l in The displacement difference of the first hydraulic cylinder is obtained by comparing it with the displacement feedback signal l of the first hydraulic cylinder, as shown below:

[0034] e l =l in -l;

[0035] In the formula: e l Indicates the displacement difference of the first hydraulic cylinder; l represents the displacement feedback signal of the first hydraulic cylinder;

[0036] Design an error compensation controller C1(s) to compensate for errors and eliminate steady-state errors;

[0037] Based on the pitch load prediction value T Z A feedforward compensation control C3(s) is designed for compensation;

[0038] Adding the three control components together, we obtain the speed control command ω of the servo motor in the first EHA drive unit. in As shown below:

[0039] ω in (s)=e l C1(s)+l in C2(s)+F z C3(s);

[0040] In the formula: ω in (s) represents the speed control command of the servo motor in the first EHA drive unit; C1(s) represents the first error compensation control loop; C2(s) represents the second feedforward control loop; C3(s) represents the third feedforward compensation control loop; F z The parameter represents the feedback parameter of the third feedforward compensation control loop; s represents the differential operator.

[0041] Servo driver controls servo motor speed by tracking speed command ω in The bidirectional fixed displacement hydraulic pump is driven to supply oil to the first hydraulic cylinder and control the movement of the first hydraulic cylinder.

[0042] Preferably, in step 4, the establishment of the control loop for the second EHA drive unit based on the predicted pitch load value and the speed error feedback signal of the first EHA drive unit specifically involves:

[0043] The feedforward control loop C5(s) is designed to implement the driving force command F of the second hydraulic cylinder. in Rapid tracking; second hydraulic cylinder driving force command signal F in Feedback signal p of the driving force of the second hydraulic cylinder B By comparing with K3, the difference in driving force of the second hydraulic cylinder is obtained, as shown below:

[0044] e f =F in -p B K1;

[0045] In the formula: e f Indicates the difference in driving force of the second hydraulic cylinder; F in This indicates the driving force command signal for the second hydraulic cylinder; p B K represents the high-pressure chamber pressure of the second hydraulic cylinder; K1 represents the feedback coefficient.

[0046] The design of the error compensation controller C4(s) compensates for the error and eliminates the steady-state error; at the same time, the pitch controller feeds back the difference based on the speed of the first hydraulic cylinder, as shown below:

[0047] e v =l in s-ls;

[0048] In the formula: e v This represents the speed difference between the pitch controller and the first hydraulic cylinder; s represents the differential operator.

[0049] Design a feedforward compensation controller C6(s) for speed compensation;

[0050] Adding the three control loops mentioned above together yields the torque control command T for the servo motor in the second EHA drive unit. in As shown below:

[0051] T in (s)=e f C4(s)+F in C5(s)+e v C6(s);

[0052] In the formula: T in (s) represents the torque control command of the servo motor in the second EHA drive unit; C4(s) represents the second error compensation control loop; C5(s) represents the fifth feedforward compensation control loop; C6(s) represents the sixth feedforward compensation control loop;

[0053] Servo driver controls servo motor torque tracking torque command T in The bidirectional constant displacement hydraulic pump is driven to supply oil to the second hydraulic cylinder, thereby generating driving force in the second hydraulic cylinder.

[0054] The second aspect of the present invention proposes a pitch system based on the aforementioned pitch cooperative control method for a dual EHA-driven independent pitch system, which can realize the cooperative control of the dual EHA-driven independent pitch system. The pitch system includes: a wind turbine main control system, a pitch controller, a first EHA drive unit and a second EHA drive unit, and a pitch bearing.

[0055] The wind turbine main control system is mainly used for the overall status detection and control of the wind turbine, and controls the pitch system in combination with the unit's operating status and wind conditions.

[0056] The pitch controller converts the pitch angle command of the main control system into the speed command of the first servo motor of the first EHA drive unit, and sets the torque command of the servo motor of the second EHA drive unit in combination with the predicted pitch load and the pressure feedback of the two chambers of the hydraulic cylinder; the pitch controller performs position control and pressure control on the first EHA drive unit and the second EHA drive unit respectively, so as to realize the dynamic high-precision tracking of the pitch angle command of the main control system by the dual EHA drive independent pitch system.

[0057] The first EHA drive unit includes a first servo driver, a first servo motor, a first bidirectional constant displacement pump, a first hydraulically controlled check valve, a second hydraulically controlled check valve, a first relief valve, a second relief valve, a first solenoid switch valve, a second solenoid switch valve, a third solenoid switch valve, a fourth solenoid switch valve, a fifth solenoid switch valve, a sixth solenoid switch valve, a first closed oil tank, a first emergency accumulator, a first hydraulic cylinder, a first displacement sensor, a first rodless chamber pressure sensor, and a first rod chamber pressure sensor; the first servo driver is connected to the first servo motor, controlling the speed of the first servo motor in relation to... Torque; the first servo motor and the first bidirectional constant displacement pump are coaxially connected; the P port of the first bidirectional constant displacement pump is connected to the P port of the fifth solenoid switch valve, the P port of the sixth solenoid switch valve, the Q port of the second relief valve, the Q port of the second hydraulic check valve, and the control oil port of the first hydraulic check valve, respectively; the Q port of the bidirectional constant displacement pump is connected to the P port of the first solenoid switch valve, the P port of the second relief valve, the Q port of the first hydraulic check valve, and the control oil port of the second hydraulic check valve, respectively; the P port of the first hydraulic check valve is connected to the Q port of the first relief valve, the P port of the second solenoid switch valve, and the control oil port of the first hydraulic check valve, respectively. The oil port of a closed oil tank, the P port of the third solenoid valve, the Q port of the second relief valve, and the P port of the second hydraulic check valve are connected; the P port of the fourth solenoid valve is connected to the oil port of the first emergency accumulator and the Q port of the sixth solenoid valve; the rodless chamber of the first hydraulic cylinder is connected to the first rodless chamber pressure sensor, the Q port of the third solenoid valve, the Q port of the fourth solenoid valve, and the Q port of the fifth solenoid valve; the rod chamber of the first hydraulic cylinder is connected to the Q port of the first solenoid valve, the P port of the second solenoid valve, and the first rod chamber pressure sensor; the first A displacement sensor is installed on the first hydraulic cylinder to monitor the displacement of the piston rod of the hydraulic cylinder; the second EHA drive unit includes a second servo driver, a second servo motor, a second bidirectional constant displacement pump, a third hydraulic control check valve, a fourth hydraulic control check valve, a third relief valve, a fourth relief valve, a seventh solenoid switch valve, an eighth solenoid switch valve, a ninth solenoid switch valve, a tenth solenoid switch valve, an eleventh solenoid switch valve, a twelfth solenoid switch valve, a second closed oil tank, a second emergency accumulator, a second hydraulic cylinder, a second displacement sensor, a second rodless chamber pressure sensor, and a second rod chamber pressure sensor;

[0058] The second servo driver is connected to the second servo motor to control the speed and torque of the second servo motor; the second servo motor and the second bidirectional constant displacement pump are coaxially connected; the P port of the second bidirectional constant displacement pump is connected to the P port of the eleventh solenoid valve, the P port of the twelfth solenoid valve, the Q port of the fourth relief valve, the Q port of the fourth hydraulic check valve, and the control port of the third hydraulic check valve, respectively; the Q port of the second bidirectional constant displacement pump is connected to the P port of the seventh solenoid valve, the P port of the fourth relief valve, the Q port of the third hydraulic check valve, and the control port of the fourth hydraulic check valve, respectively; the P port of the third hydraulic check valve is connected to the Q port of the third relief valve and the P port of the eighth solenoid valve, respectively. The oil port of the second closed oil tank, the P port of the ninth solenoid valve, the Q port of the fourth relief valve, and the P port of the fourth hydraulic check valve are connected; the P port of the tenth solenoid valve is connected to the oil port of the second emergency accumulator and the Q port of the twelfth solenoid valve; the rodless chamber of the second hydraulic cylinder is connected to the second rodless chamber pressure sensor, the Q port of the ninth solenoid valve, the Q port of the tenth solenoid valve, and the Q port of the eleventh solenoid valve; the rod chamber of the second hydraulic cylinder is connected to the Q port of the seventh solenoid valve, the port of the eighth solenoid valve, and the second rod chamber pressure sensor; the second displacement sensor is installed on the second hydraulic cylinder to monitor the displacement of the piston rod of the second hydraulic cylinder.

[0059] The outer ring of the pitch bearing is fixed to the hub, and the inner ring of the pitch bearing is fixedly connected to the blade root and the torque transmission disc. The first hydraulic cylinder and the second hydraulic cylinder are installed in parallel opposite positions. The tail of the rod chamber of the first hydraulic cylinder and the second hydraulic cylinder are respectively connected to the hub through hinges. The piston rod ends of the first hydraulic cylinder and the second hydraulic cylinder are respectively connected to the torque transmission disc through spherical bearings.

[0060] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0061] (1) The dual EHA driven independent pitch system adopted in this invention includes two EHA drive units. The highly integrated closed-loop pump-controlled hydraulic system (EHA) drive unit does not require hydraulic slip rings and long pipelines, reducing the risk of oil leakage and making maintenance convenient. The two EHA drive units are installed in parallel opposite each other and work together to drive the blade pitch, resulting in a large driving force and a small radial off-center load.

[0062] (2) By predicting the pitch load and performing high-precision position control and pressure compensation control on the first EHA drive unit and the second EHA drive unit respectively, the present invention can achieve high-precision and high-dynamic tracking of the pitch angle command of the main control system by the dual EHA drive independent pitch system. Attached Figure Description

[0063] Figure 1 This is a control block diagram of the pitch cooperative control method for a dual EHA-driven independent pitch system according to an embodiment of the present invention.

[0064] Figure 2 This is a schematic diagram of the dual EHA-driven independent pitch system according to an embodiment of the present invention;

[0065] Figure 3 This is a schematic diagram of the pitch actuator structure according to an embodiment of the present invention;

[0066] Figure 4 This is a schematic diagram of the hydraulic rod structure of the pitch actuator according to an embodiment of the present invention;

[0067] Figure 5 This is a flowchart of the pitch system control mode switching method in an embodiment of the present invention;

[0068] Figure 6 This is a schematic diagram of the control system of the pitch cooperative control method in an embodiment of the present invention;

[0069] Figure 7 This is a flowchart of the training process for the pitch system load and unit power prediction model in an embodiment of the present invention.

[0070] Key reference numerals:

[0071] 1. First servo driver; 2. First servo motor; 3. First bidirectional constant displacement pump; 4. First hydraulically controlled check valve; 5. First relief valve; 6. First solenoid switch valve; 7. Second solenoid switch valve; 8. First displacement sensor; 9. Torque transmission disc; 10. Pitch bearing; 11. First hydraulic cylinder; 12. First rodless chamber pressure sensor; 13. First closed oil tank; 14. Third solenoid switch valve; 15. Fourth solenoid switch valve; 16. Fifth solenoid switch valve; 17. First emergency accumulator; 18. Sixth solenoid switch valve; 19. Second relief valve; 20. Second hydraulically controlled check valve; 21. First rod chamber pressure sensor; 22. Pitch controller; 23. Main control system; 24. Second servo motor. 25. Driver; 26. Second servo motor; 27. Second bidirectional constant displacement pump; 28. Third hydraulic check valve; 29. ​​Third relief valve; 30. Seventh solenoid switch valve; 31. Eighth solenoid switch valve; 32. Second rod chamber pressure sensor; 33. Second displacement sensor; 34. Second hydraulic cylinder; 35. Second rodless chamber pressure sensor; 36. Second closed oil tank; 37. Ninth solenoid switch valve; 38. Tenth solenoid switch valve; 39. Eleventh solenoid switch valve; 40. Second emergency accumulator; 41. Twelfth solenoid switch valve; 42. Fourth relief valve; 43. Fourth hydraulic check valve; 44. Hub; 45. Blade; A. First EHA drive unit; B. Second EHA drive unit. Detailed Implementation

[0072] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0073] The dual EHA-driven independent pitch control system used in this embodiment of the invention includes two EHA drive units. The highly integrated closed-loop pump-controlled hydraulic system (EHA) drive unit eliminates the need for hydraulic slip rings and long pipelines, reducing the risk of oil leakage and facilitating maintenance. The two EHA drive units are installed in parallel opposite positions, collaboratively driving the blade pitch, resulting in high driving force and low radial off-center load. By predicting pitch load and performing high-precision position control and pressure compensation control on the first EHA drive unit A and the second EHA drive unit B respectively, the dual EHA-driven independent pitch control system can achieve high-precision and high-dynamic tracking of the pitch angle commands from the main control system. Figure 1 The diagram shown is a control block diagram of the pitch cooperative control method for a dual EHA-driven independent pitch system according to an embodiment of the present invention.

[0074] This invention provides a pitch cooperative control method for a dual EHA-driven independent pitch system, such as... Figure 2 The diagram shown is a flowchart of an embodiment of the present invention; to demonstrate the applicability of the present invention, it is applied to an example, specifically including the following steps:

[0075] S1: Based on wind farm SCADA and wind turbine data, establish a prediction model for pitch system load and turbine power.

[0076] Acquire long-term SCADA data and wind turbine data from the wind farm, clean the data, and perform normalization processing to obtain the normalized result x of the state variable and the normalized result y of the actual variable.

[0077] The content of medium- and long-term SCADA data and wind turbine data covers all wind conditions. in ≤v≤v out The running status data, v in Indicates the cut-in wind speed, v out This indicates the cut-out wind speed; data cleaning is performed to remove data from units that are shut down, data with sensor errors, and data causing interference; long-term SCADA data and wind turbine data from the wind farm are acquired, the data is cleaned, and normalization is performed. The processing steps are as follows:

[0078]

[0079] In the formula: x norm This represents the normalization result of the state variable; x s The input value of the state variable; x min Represents the minimum value of the state variable; x max y represents the maximum value of the state variable; y represents the input value of the actual variable; y norm This represents the normalized result of the actual quantity; y maxThis represents the maximum value of the actual quantity; x = {v, w, θ, β, Δψ} includes the wind speed in the wind turbine plane v, the wind turbine rotation speed w, the blade azimuth angle θ, the blade pitch angle β, and the yaw angle error Δψ.

[0080] The normalized result of the state variables x = {v, w, θ, β, Δψ} is used as the input to the neural network, and the normalized result of the actual variables y = {P, T} Z As the output of the neural network, the pitch system load and unit power prediction model is trained using an artificial neural network, such as... Figure 7 The diagram shown is a flowchart of the training process for the pitch system load and turbine power prediction model in an embodiment of the present invention. The resulting pitch system load and turbine power prediction model is shown below:

[0081]

[0082] In the formula: T Z f1 represents the actual value of pitch load; P represents the actual value of generator power; x = {v, w, θ, β, Δψ} represents the normalized result of the state variables; v represents the wind speed in the rotor plane; w represents the rotor speed; θ represents the blade azimuth angle; β represents the blade pitch angle; Δψ represents the yaw angle error; f1 represents the neural network model of pitch load; f2 represents the neural network model of generator power.

[0083] S2: Using the pitch load and unit power prediction model, the predicted values ​​of the pitch load and unit power of the unit are obtained.

[0084] The unit's main control system monitors and collects the state variables x = {v, w, θ, β, Δψ} in real time; substituting the normalized state variables into the unit's pitch load model and power prediction model, the predicted values ​​of the unit's pitch load and power are obtained as T. Zn orm, P norm Then, inverse normalization is performed, as shown in the following process:

[0085]

[0086] In the formula: y represents the normalized result of the actual quantity; y norm This represents the predicted pitch load of the generator unit; y max This represents the predicted power output of the generating unit; y min This represents the minimum value of the actual quantity.

[0087] S3: Based on the pitch angle command and the predicted pitch load, establish the control loop of the first EHA drive unit A.

[0088] The feedforward control loop C2(s) is designed to implement the displacement command of the first hydraulic cylinder. in Rapid tracking; the displacement command signal of the first hydraulic cylinder l inThe displacement difference of the first hydraulic cylinder is obtained by comparing it with the displacement feedback signal l of the first hydraulic cylinder, as shown below:

[0089] e l =l in -l;

[0090] In the formula: e l represents the displacement difference of the first hydraulic cylinder; l represents the displacement feedback signal of the first hydraulic cylinder.

[0091] The error compensation controller C1(s) is designed to compensate for the error and eliminate the steady-state error.

[0092] Based on the pitch load prediction value T Z A feedforward compensation control C3(s) is designed for compensation.

[0093] Adding the above three control components together yields the speed control command ω for the first servo motor in the first EHA drive unit A. in As shown below:

[0094] ω in (s)=e l C1(s)+l in C2(s)+F z C3(s);

[0095] In the formula: ω in (s) represents the speed control command of the servo motor in the first EHA drive unit; C1(s) represents the first error compensation control loop; C2(s) represents the second feedforward control loop; C3(s) represents the third feedforward compensation control loop; F z represents the feedback parameter of the third feedforward compensation control loop; s represents the differential operator.

[0096] The first servo driver controls the first servo motor to track the speed command ω. in The first bidirectional fixed displacement hydraulic pump 3 is driven to supply oil to the first hydraulic cylinder and control the movement of the first hydraulic cylinder.

[0097] The pitch angle command signal is converted into a displacement signal for the first hydraulic cylinder, which controls the displacement of the hydraulic cylinder piston rod in the pitch control system. The calculation model for the displacement command signal of the first hydraulic cylinder is as follows:

[0098]

[0099] In the formula: l in This indicates the displacement command signal for the first hydraulic cylinder; R represents the rotation radius of the piston rod end of the first hydraulic cylinder; H represents the distance from the mounting hinge of the first hydraulic cylinder to the center of the blade; α represents the angle between the rotation radius of the piston rod end of the first hydraulic cylinder and the line connecting the mounting hinge of the first hydraulic cylinder to the center of the blade at the 0° pitch angle position; Lmin This indicates the distance from the end of the piston rod to the hinge position of the first hydraulic cylinder when the pitch angle is 0°.

[0100] The pitch controller will transmit the pitch angle command β from the main control system. in The displacement command signal l of the first hydraulic cylinder is converted into in The control loop of the first EHA drive unit A is designed to realize the motion control of the first hydraulic cylinder.

[0101] S4: Based on the predicted pitch load value and the speed error feedback signal of the first EHA drive unit A, establish the control loop of the second EHA drive unit B.

[0102] The feedforward control loop C5(s) is designed to implement the driving force command F of the second hydraulic cylinder. in Rapid tracking; second hydraulic cylinder driving force command signal F in Feedback signal p of the driving force of the second hydraulic cylinder B By comparing with K3, the difference in driving force of the second hydraulic cylinder is obtained, as shown below:

[0103] e f =F in -p B K1;

[0104] In the formula: e f This indicates the difference in driving force between the second hydraulic cylinder and the second hydraulic cylinder; F in This indicates the driving force command signal for the second hydraulic cylinder; p B K represents the high-pressure chamber pressure of the second hydraulic cylinder; K1 represents the feedback coefficient.

[0105] The design of the error compensation controller C4(s) compensates for the error and eliminates the steady-state error; at the same time, the pitch controller feeds back the difference based on the speed of the first hydraulic cylinder, as shown below:

[0106] e v =l in s-ls;

[0107] In the formula: e v represents the speed difference of the pitch controller based on the speed feedback of the first hydraulic cylinder; s represents the differential operator.

[0108] Design a feedforward compensation controller C6(s) for speed compensation.

[0109] Adding the above three control components together yields the torque control command T for the second servo motor in the second EHA drive unit A. in As shown below:

[0110] T in (s)=e f C4(s)+Fin C5(s)+e v C6(s);

[0111] In the formula: T in C4(s) represents the torque control command of the second servo motor in the second EHA drive unit B; C5(s) represents the second error compensation control loop; C6(s) represents the fifth feedforward compensation control loop; and C6(s) represents the sixth feedforward compensation control loop.

[0112] The second servo driver controls the second servo motor to track torque command T. in The second bidirectional constant displacement hydraulic pump is driven to supply oil to the second hydraulic cylinder, thereby generating driving force in the second hydraulic cylinder.

[0113] The pitch controller will predict the pitch load T. Znorm The driving force command F is converted into that of the second hydraulic cylinder. in The relationship between the two is as follows:

[0114]

[0115] In the formula: F in Indicates the driving force command parameter for the second hydraulic cylinder; T Znorm This represents the predicted pitch load of the generator unit.

[0116] S5: Coordinate the control of the first EHA drive unit A and the second EHA drive unit B to achieve coordinated control of the two EHA drive units.

[0117] The first EHA drive unit A and the second EHA drive unit B in S3 and 4 are used to collaboratively drive the blade pitch control, enabling dynamic high-precision tracking of the pitch angle command from the main control system by the dual EHA-driven independent pitch control system, and ultimately achieving collaborative control of the dual EHA drive units. Figure 5 The diagram shows a flowchart of the pitch system control mode switching method in an embodiment of the present invention.

[0118] like Figure 6 The diagram shows the control system principle of the pitch cooperative control method in this embodiment of the invention; Table 1 shows the efficiency comparison data of the EHA-driven pitch and valve-controlled cylinder pitch systems implemented by the control principle of this method. It can be clearly seen that the system efficiency of this method is higher than that of the valve-controlled cylinder pitch system.

[0119] Table 1. Efficiency Comparison of EHA-Driven Pitch and Valve-Controlled Cylinder Pitch Systems

[0120] System efficiency ≈60％ ≤38.5％

[0121] The second aspect of the present invention proposes a pitch system for a pitch cooperative control method of a dual EHA-driven independent pitch system, which can realize the cooperative control of the dual EHA-driven independent pitch system. The main structure of the pitch system includes: a wind turbine main control system 23, a pitch controller 22, a first EHA drive unit A, a second EHA drive unit B, and a pitch bearing 10.

[0122] The wind turbine main control system 23 is mainly used for the overall status detection and control of the wind turbine, and controls the pitch system in combination with the operating status of the unit and the wind conditions.

[0123] The pitch controller 22 converts the pitch angle command from the main control system 23 into the speed command of the first servo motor 2 of the first EHA drive unit A, and sets the torque command of the servo motor B of the second EHA drive unit B based on the predicted pitch load and the pressure feedback of the two chambers of the hydraulic cylinder; for example Figure 3 The diagram shows a schematic of the pitch actuator structure according to an embodiment of the present invention. The pitch controller 22 performs position control and pressure control on the first EHA drive unit A and the second EHA drive unit B, respectively, to achieve dynamic high-precision tracking of the pitch angle command from the main control system 23 by the dual EHA drive independent pitch system. Figure 4 The diagram shown is a schematic diagram of the hydraulic rod structure of the pitch actuator according to an embodiment of the present invention.

[0124] The first EHA drive unit A includes a first servo driver 1, a first servo motor 2, a first bidirectional constant displacement pump 3, a first hydraulic control check valve 4, a second hydraulic control check valve 20, a first relief valve 5, a second relief valve 19, a first electromagnetic switch valve 6, a second electromagnetic switch valve 7, a third electromagnetic switch valve 14, a fourth electromagnetic switch valve 15, a fifth electromagnetic switch valve 16, a sixth electromagnetic switch valve 18, a first closed oil tank 13, a first emergency accumulator 17, a first hydraulic cylinder 11, a first displacement sensor 8, a first rodless chamber pressure sensor 12, and a first rod chamber pressure sensor 21. The first servo driver 1 is connected to the first servo motor 2, controlling the speed and torque of the first servo motor 2; the first servo motor 2 is coaxially connected to the first bidirectional constant displacement pump 3; the P port of the first bidirectional constant displacement pump 3 is connected to the P port of the fifth solenoid valve 16, the P port of the sixth solenoid valve 18, the Q port of the second overflow valve 19, the Q port of the second hydraulic check valve 20, and the control oil port of the first hydraulic check valve 4, respectively; the Q port of the bidirectional constant displacement pump 3 is connected to the P port of the first solenoid valve 6, the P port of the second overflow valve 19, the Q port of the first hydraulic check valve 4, and the control oil port of the second hydraulic check valve 20, respectively; the P port of the first hydraulic check valve 4 is connected to the Q port of the first overflow valve 5, the P port of the second solenoid valve 7, and the first closed oil tank, respectively. The oil port of the first hydraulic cylinder 13, the P port of the third solenoid valve 14, the Q port of the second relief valve 19, and the P port of the second hydraulic check valve 20 are connected; the P port of the fourth solenoid valve 15 is connected to the oil port of the first emergency accumulator 17 and the Q port of the sixth solenoid valve 18 respectively; the rodless chamber of the first hydraulic cylinder 11 is connected to the first rodless chamber pressure sensor 12, the Q port of the third solenoid valve 14, the Q port of the fourth solenoid valve 15, and the Q port of the fifth solenoid valve 16 respectively; the rod chamber of the first hydraulic cylinder 11 is connected to the Q port of the first solenoid valve 6, the P port of the second solenoid valve 7, and the first rod chamber pressure sensor 21 respectively; the first displacement sensor 8 is installed on the first hydraulic cylinder 11 to monitor the displacement of the piston rod of the hydraulic cylinder 11. The second EHA drive unit B includes a second servo driver 24, a second servo motor 25, a second bidirectional constant displacement pump 26, a third hydraulic control check valve 27, a fourth hydraulic control check valve 42, a third relief valve 28, a fourth relief valve 41, a seventh electromagnetic switch valve 29, an eighth electromagnetic switch valve 30, a ninth electromagnetic switch valve 36, a tenth electromagnetic switch valve 37, an eleventh electromagnetic switch valve 38, a twelfth electromagnetic switch valve 40, a second closed oil tank 35, a second emergency accumulator 39, a second hydraulic cylinder 33, a second displacement sensor 32, a second rodless chamber pressure sensor 34, and a second rod chamber pressure sensor 31.

[0125] The second servo driver 24 is connected to the second servo motor 25, controlling the speed and torque of the second servo motor 25; the second servo motor 25 is coaxially connected to the second bidirectional constant displacement pump 26; the P port of the second bidirectional constant displacement pump 26 is connected to the P port of the eleventh solenoid switch valve 38, the P port of the twelfth solenoid switch valve 40, the Q port of the fourth relief valve 41, the Q port of the fourth hydraulic control check valve 42, and the control oil port of the third hydraulic control check valve 27, respectively; the Q port of the second bidirectional constant displacement pump 26 is connected to the P port of the seventh solenoid switch valve 29, the P port of the fourth relief valve 41, the Q port of the third hydraulic control check valve 27, and the control oil port of the fourth hydraulic control check valve 42, respectively; the P port of the third hydraulic control check valve 27 is connected to the Q port of the third relief valve 28, the P port of the eighth solenoid switch valve 30, and the control oil port of the eleventh solenoid switch valve 38, the twelfth solenoid switch valve 40, the Q port of the fourth relief valve 41, the Q port of the fourth hydraulic control check valve 42, and the control oil port of the fourth hydraulic control check valve 42, respectively; the P port of the third hydraulic control check valve 27 is connected to the Q port of the third relief valve 28, the P port of the eighth solenoid switch valve 30, and the control oil port of the twelfth solenoid switch valve 26, respectively. The oil port of the second closed oil tank 35, the P port of the ninth solenoid valve 36, the Q port of the fourth relief valve 41, and the P port of the fourth hydraulic check valve 42 are connected; the P port of the tenth solenoid valve 37 is connected to the oil port of the second emergency accumulator 39 and the Q port of the twelfth solenoid valve 40 respectively; the rodless chamber of the second hydraulic cylinder 33 is connected to the second rodless chamber pressure sensor 34, the Q port of the ninth solenoid valve 36, the Q port of the tenth solenoid valve 37, and the Q port of the eleventh solenoid valve 38 respectively; the rod chamber of the second hydraulic cylinder 33 is connected to the Q port of the seventh solenoid valve 29, the P port of the eighth solenoid valve 30, and the second rod chamber pressure sensor 31 respectively; the second displacement sensor 32 is installed on the second hydraulic cylinder 33 to monitor the displacement of the piston rod of the second hydraulic cylinder 33.

[0126] The outer ring of the pitch bearing 10 is fixed on the hub 43, and the inner ring of the pitch bearing 10 is fixedly connected to the root of the blade 44 and the torque transmission disk 9. The first hydraulic cylinder 11 and the second hydraulic cylinder 33 are installed in parallel opposite positions. The tail of the rod chamber of the first hydraulic cylinder 11 and the second hydraulic cylinder 33 are respectively connected to the hub 43 by hinges. The piston rod ends of the first hydraulic cylinder 11 and the second hydraulic cylinder 33 are respectively connected to the torque transmission disk 9 by spherical bearings.

[0127] In summary, the prediction results of the pitch cooperative control method for the dual EHA-driven independent pitch system in this case demonstrate its excellent effectiveness.

[0128] (1) The dual EHA driven independent pitch system used in the embodiments of the present invention includes two EHA drive units. The highly integrated closed-loop pump-controlled hydraulic system (EHA) drive unit does not require hydraulic slip rings and long pipelines, reducing the risk of oil leakage and making maintenance convenient. The two EHA drive units are installed in parallel opposite each other and work together to drive the blade pitch, resulting in a large driving force and a small radial off-center load.

[0129] (2) The embodiments of the present invention predict the pitch load and perform high-precision position control and pressure compensation control on the first EHA drive unit and the second EHA drive unit respectively, so as to realize the high-precision and high-dynamic tracking of the pitch angle command of the main control system by the dual EHA drive independent pitch system.

[0130] (3) The efficiency of this method is compared with that of the valve-controlled cylinder pitch system in the embodiments of the present invention. It can be clearly seen that the efficiency of the system using this method is higher than that of the valve-controlled cylinder pitch system.

[0131] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A pitch coordination control method for a dual EHA-driven independent pitch system, characterized in that, It includes the following steps: Step 1: Based on wind farm SCADA and wind turbine data, establish a prediction model for pitch system load and turbine power; Acquire medium- and long-term SCADA data and wind turbine data from the wind farm, clean the data, and perform normalization processing to obtain the normalized results of the state variables. Normalized results of actual quantities ; Normalize the state variables The normalized result of the actual quantity is used as input to the neural network. As the output of the neural network, the pitch system load and turbine power prediction model is trained using an artificial neural network to obtain the pitch system load and turbine power prediction model, as shown below: ； In the formula: This indicates the actual value of the pitch load; This indicates the actual power output of the generator unit; This represents the normalization result of the state variables; Indicates the wind speed in the plane of the wind turbine; Indicates the wind turbine rotation speed; Indicates the blade azimuth angle; Indicates the blade pitch angle; Indicates the yaw angle error; Represents the neural network model of pitch load; Represents the neural network model of unit power; Step 2: Use the pitch load and unit power prediction model to obtain the predicted values ​​of the pitch load and unit power of the unit; The unit's main control system monitors and collects status variables in real time. Substituting the normalized state variables into the unit pitch load model and the unit power prediction model, we obtain the unit pitch load and unit power prediction values. , Then, inverse normalization is performed, as shown in the following process: ； In the formula: This represents the normalized result of the actual quantity; This represents the predicted pitch load of the generator unit; This represents the predicted power output of the generating unit; This represents the minimum value of the actual quantity; Step 3: Establish the control loop of the first EHA drive unit based on the pitch angle command and the predicted pitch load value; Speed ​​control commands for the servo motor in the first EHA drive unit As shown below: ； In the formula: This indicates the speed control command for the servo motor in the first EHA drive unit; This indicates the first error compensation control stage; This indicates the second feedforward control loop; This indicates the third feedforward compensation control stage; The parameter represents the feedback parameter of the third feedforward compensation control loop; s represents the differential operator. The pitch angle command signal is converted into a displacement signal for the first hydraulic cylinder, which controls the displacement of the hydraulic cylinder piston rod in the pitch control system. The calculation model for the displacement command signal of the first hydraulic cylinder is as follows: ； In the formula: This indicates the displacement command signal for the first hydraulic cylinder; This indicates the radius of rotation of the piston rod end of the first hydraulic cylinder; This indicates the distance from the mounting hinge of the first hydraulic cylinder to the center of the blade; This represents the angle between the radius of rotation of the piston rod end of the first hydraulic cylinder and the line connecting the mounting hinge of the first hydraulic cylinder to the center of the blade when the blade pitch angle is 0°. This indicates the distance from the end of the piston rod to the hinge position of the first hydraulic cylinder when the pitch angle is 0°. The pitch controller transmits the pitch angle command from the main control system. This is converted into a displacement command signal for the first hydraulic cylinder. The control loop of the first EHA drive unit is designed to realize the motion control of the first hydraulic cylinder; Step 4: Based on the predicted pitch load value and the speed error feedback signal of the first EHA drive unit, establish the control loop of the second EHA drive unit; Torque control commands for the servo motor in the second EHA drive unit As shown below; ； In the formula: This indicates the torque control command for the servo motor in the second EHA drive unit; This indicates the second error compensation control stage; This indicates the fifth feedforward compensation control stage; This indicates the sixth feedforward compensation control stage; The pitch controller will predict the pitch load. Converted into driving force command for the second hydraulic cylinder The relationship between the two is as follows: ； In the formula: This indicates the driving force command parameters for the second hydraulic cylinder; This represents the predicted pitch load of the generator unit; Step 5: Coordinate the control of the first EHA drive unit and the second EHA drive unit to achieve coordinated control of the two EHA drive units; The first EHA drive unit and the second EHA drive unit in steps 3 and 4 work together to drive the blade pitch, thereby realizing the dynamic high-precision tracking of the pitch angle command of the main control system by the dual EHA drive independent pitch system, and finally realizing the coordinated control of the dual EHA drive units.

2. The pitch coordination control method for a dual EHA-driven independent pitch system according to claim 1, characterized in that, Step 1, which involves acquiring long-term SCADA data and wind turbine data from the wind farm, cleaning the data, and performing normalization, specifically includes: The long-term SCADA data and wind turbine data for the wind farm cover all wind conditions. The running status data, Indicates the cut-in wind speed. Indicates the cut-out wind speed; The data cleaning process involves removing data from units that are out of service, data with sensor errors, and data that is subject to interference. Acquire long-term SCADA data and wind turbine data from the wind farm, clean the data, and perform normalization processing. The processing steps are as follows: ； In the formula: x norm This represents the normalization result of the state variables; The input value of the state variable; x min Represents the minimum value of the state variable; x max This represents the maximum value of the state variable; The input value represents the actual quantity; This represents the normalized result of the actual quantity; This represents the maximum value of the actual quantity; Including wind speed in the plane of the wind turbine Wind turbine speed Blade azimuth angle Blade pitch angle and yaw angle error .

3. The pitch coordination control method for a dual EHA-driven independent pitch system according to claim 1, characterized in that, Step 3, which establishes the control loop for the first EHA drive unit based on the pitch angle command and the predicted pitch load, specifically involves: Design feedforward control loop Implement displacement command for the first hydraulic cylinder Rapid tracking; the displacement command signal of the first hydraulic cylinder Displacement feedback signal of the first hydraulic cylinder By comparison, the displacement difference of the first hydraulic cylinder is obtained, as shown below: ； In the formula: e l Indicates the displacement difference of the first hydraulic cylinder; l represents the displacement feedback signal of the first hydraulic cylinder; Design error compensation controller Error compensation is performed to eliminate steady-state error; Based on pitch load prediction values Design feedforward compensation control Provide compensation; Adding the three control components together yields the speed control command for the servo motor in the first EHA drive unit. ; Servo driver controls servo motor speed and tracks speed commands The bidirectional fixed displacement hydraulic pump is driven to supply oil to the first hydraulic cylinder and control the movement of the first hydraulic cylinder.

4. The pitch coordination control method for a dual EHA-driven independent pitch system according to claim 1, characterized in that, Step 4, which establishes the control loop for the second EHA drive unit based on the predicted pitch load value and the speed error feedback signal of the first EHA drive unit, specifically involves: Design feedforward control loop To implement the driving force command for the second hydraulic cylinder Rapid tracking; second hydraulic cylinder drive force command signal Feedback signal of driving force of the second hydraulic cylinder By comparison, the difference in driving force of the second hydraulic cylinder is obtained, as shown below: ； In the formula: e f Indicates the difference in driving force of the second hydraulic cylinder; F in This indicates the driving force command signal for the second hydraulic cylinder; p B K represents the high-pressure chamber pressure of the second hydraulic cylinder; K1 represents the feedback coefficient. Design error compensation controller Error compensation is performed to eliminate steady-state error; simultaneously, the pitch controller provides feedback on the speed difference based on the first hydraulic cylinder, as shown below: ； In the formula: e v This represents the speed difference between the pitch controller and the first hydraulic cylinder; s represents the differential operator. Design a feedforward compensation controller Perform speed compensation; Adding the three control components together yields the torque control command for the servo motor in the second EHA drive unit. ; Servo driver controls servo motor torque tracking torque command The bidirectional constant displacement hydraulic pump is driven to supply oil to the second hydraulic cylinder, thereby generating driving force in the second hydraulic cylinder.

5. A pitch system for implementing the pitch cooperative control method of the dual EHA-driven independent pitch system according to any one of claims 1 to 4, characterized in that: It can realize the coordinated control of the dual EHA drive independent pitch system. The pitch system includes: wind turbine main control system, pitch controller, first EHA drive unit, second EHA drive unit and pitch bearing; The wind turbine main control system is mainly used for the overall status detection and control of the wind turbine, and controls the pitch system in combination with the unit's operating status and wind conditions. The pitch controller converts the pitch angle command of the main control system into the speed command of the first servo motor of the first EHA drive unit, and sets the torque command of the servo motor of the second EHA drive unit in combination with the predicted pitch load and the pressure feedback of the two chambers of the hydraulic cylinder; the pitch controller performs position control and pressure control on the first EHA drive unit and the second EHA drive unit respectively, so as to realize the dynamic tracking of the pitch angle command of the main control system by the dual EHA drive independent pitch system. The first EHA drive unit includes a first servo driver, a first servo motor, a first bidirectional constant displacement pump, a first hydraulically controlled check valve, a second hydraulically controlled check valve, a first relief valve, a second relief valve, a first solenoid switch valve, a second solenoid switch valve, a third solenoid switch valve, a fourth solenoid switch valve, a fifth solenoid switch valve, a sixth solenoid switch valve, a first closed oil tank, a first emergency accumulator, a first hydraulic cylinder, a first displacement sensor, a first rodless chamber pressure sensor, and a first rod chamber pressure sensor; the first servo driver is connected to the first servo motor, controlling the speed of the first servo motor in relation to... Torque; the first servo motor and the first bidirectional constant displacement pump are coaxially connected; the P port of the first bidirectional constant displacement pump is connected to the P port of the fifth solenoid switch valve, the P port of the sixth solenoid switch valve, the Q port of the second relief valve, the Q port of the second hydraulic check valve, and the control oil port of the first hydraulic check valve, respectively; the Q port of the bidirectional constant displacement pump is connected to the P port of the first solenoid switch valve, the P port of the second relief valve, the Q port of the first hydraulic check valve, and the control oil port of the second hydraulic check valve, respectively; the P port of the first hydraulic check valve is connected to the Q port of the first relief valve, the P port of the second solenoid switch valve, and the control oil port of the first hydraulic check valve, respectively. The oil port of a closed oil tank, the P port of the third solenoid valve, the Q port of the second relief valve, and the P port of the second hydraulic check valve are connected; the P port of the fourth solenoid valve is connected to the oil port of the first emergency accumulator and the Q port of the sixth solenoid valve; the rodless chamber of the first hydraulic cylinder is connected to the first rodless chamber pressure sensor, the Q port of the third solenoid valve, the Q port of the fourth solenoid valve, and the Q port of the fifth solenoid valve; the rod chamber of the first hydraulic cylinder is connected to the Q port of the first solenoid valve, the P port of the second solenoid valve, and the first rod chamber pressure sensor; the first A displacement sensor is installed on the first hydraulic cylinder to monitor the displacement of the piston rod of the hydraulic cylinder; the second EHA drive unit includes a second servo driver, a second servo motor, a second bidirectional constant displacement pump, a third hydraulic control check valve, a fourth hydraulic control check valve, a third relief valve, a fourth relief valve, a seventh solenoid switch valve, an eighth solenoid switch valve, a ninth solenoid switch valve, a tenth solenoid switch valve, an eleventh solenoid switch valve, a twelfth solenoid switch valve, a second closed oil tank, a second emergency accumulator, a second hydraulic cylinder, a second displacement sensor, a second rodless chamber pressure sensor, and a second rod chamber pressure sensor; The second servo driver is connected to the second servo motor to control the speed and torque of the second servo motor; the second servo motor and the second bidirectional constant displacement pump are coaxially connected; the P port of the second bidirectional constant displacement pump is connected to the P port of the eleventh solenoid valve, the P port of the twelfth solenoid valve, the Q port of the fourth relief valve, the Q port of the fourth hydraulic check valve, and the control port of the third hydraulic check valve, respectively; the Q port of the second bidirectional constant displacement pump is connected to the P port of the seventh solenoid valve, the P port of the fourth relief valve, the Q port of the third hydraulic check valve, and the control port of the fourth hydraulic check valve, respectively; the P port of the third hydraulic check valve is connected to the Q port of the third relief valve and the P port of the eighth solenoid valve, respectively. The oil port of the second closed oil tank, the P port of the ninth solenoid valve, the Q port of the fourth relief valve, and the P port of the fourth hydraulic check valve are connected; the P port of the tenth solenoid valve is connected to the oil port of the second emergency accumulator and the Q port of the twelfth solenoid valve; the rodless chamber of the second hydraulic cylinder is connected to the second rodless chamber pressure sensor, the Q port of the ninth solenoid valve, the Q port of the tenth solenoid valve, and the Q port of the eleventh solenoid valve; the rod chamber of the second hydraulic cylinder is connected to the Q port of the seventh solenoid valve, the port of the eighth solenoid valve, and the second rod chamber pressure sensor; the second displacement sensor is installed on the second hydraulic cylinder to monitor the displacement of the piston rod of the second hydraulic cylinder. The outer ring of the pitch bearing is fixed to the hub, and the inner ring of the pitch bearing is fixedly connected to the blade root and the torque transmission disc. The first hydraulic cylinder and the second hydraulic cylinder are installed in parallel opposite positions. The tail of the rod chamber of the first hydraulic cylinder and the second hydraulic cylinder are respectively connected to the hub through hinges. The piston rod ends of the first hydraulic cylinder and the second hydraulic cylinder are respectively connected to the torque transmission disc through spherical bearings.

Images