Wind turbine control based on tilt angle and yaw angle
By obtaining the inclination angle and yaw angle data of wind turbine RNA, combining the thrust data to calculate the torque, and controlling the blade pitch angle, the component wear problem caused by asymmetric loads in wind turbines is solved, and the load reduction effect without sensors is achieved .
Patent Information
- Application Number
- CN202380049380.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-08-12
- Filing Date
- 2023-06-29
- Publication Date
- 2025-02-11
AI Technical Summary
In modern large wind turbines, asymmetric loads caused by wind shear, non-zero inflow angles, wind direction fluctuations and spatial turbulence lead to accelerated wear of rotor parts, and the installation of blade load sensors is complicated.
By obtaining the tilt angle and yaw angle data of the RNA, combining the thrust data, the tilt moment and yaw moment are calculated, and the pitch angle of the blade is controlled based on these data to reduce the impact of asymmetric loads.
No need to use a blade load sensor to effectively reduce asymmetric loads on the rotor of the wind turbine and extend the service life of the parts.
Smart Images
Figure CN119422004A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of wind turbine control systems, and more particularly to controlling blade pitches to reduce tilting moments and yaw moments. Background Art
[0002] A wind turbine typically includes a tower and a rotor nacelle assembly (RNA) located on top of the tower. The RNA includes a rotor with one or more blades, and a nacelle for housing the drive train and electrical components.
[0003] In modern large wind turbines, asymmetric loads acting on the rotor increase component wear. Asymmetric loads acting on the rotor can be caused by wind shear, non-zero inflow angles, wind direction fluctuations and spatial turbulence.
[0004] The loads on wind turbines can cause wind turbine components to wear at an increased rate. Techniques such as pitch and yaw control (TYC) have been developed to control blade pitch to mitigate the effects of asymmetric loads acting on the rotor. Pitch and yaw control typically relies on measurements from blade load sensors mounted at the root of each wind turbine blade.
[0005] Not all turbines are equipped with blade load sensors, and installing blade load sensors on such wind turbines may enable control techniques that beneficially reduce the loads on the wind turbine to increase the useful life of the wind turbine's components.
[0006] One problem with installing blade load sensors is that the installation is complex, requiring drilling holes in the hub, adding new wiring, and changing hub hardware. Summary of the invention
[0007] A first aspect of the invention provides a method of controlling a wind turbine, the wind turbine comprising: a tower; and a rotor nacelle assembly (RNA) comprising a rotor and a nacelle, the rotor comprising one or more blades, the method comprising:
[0008] acquiring tilt angle data indicating the tilt angle of the RNA;
[0009] acquiring yaw angle data indicating the yaw angle of the RNA;
[0010] obtaining the thrust of the rotor;
[0011] determining a tilt moment data based on the tilt angle data and the thrust, wherein the tilt moment data indicates a tilt moment acting on the rotor about a tilt axis;
[0012] determining yaw moment data based on the yaw angle data, wherein the yaw moment data is indicative of a yaw moment acting on the rotor about a yaw axis; and
[0013] A pitch angle of one or more of the blades is controlled based on the pitch moment data and the yaw moment data.
[0014] Thereby a way of controlling a wind turbine is provided to mitigate the effects of asymmetric loads acting on the rotor without the need for the use of blade load sensors.
[0015] Optionally, the tilt angle data and / or the yaw angle data are acquired by acquiring measurement data and applying a low-pass filter and a band-pass filter to the measurement data to select 0P and 3P components, respectively, wherein 0P and 3P refer to rotor frequencies, 0P being a constant portion at zero frequency, and 3P being a frequency that occurs three times per rotor revolution.
[0016] Optionally, acquiring the tilt angle data comprises measuring the tilt angle of the RNA relative to gravity using an inclinometer, and determining the tilt angle data based on the measured tilt angle of the RNA.
[0017] Optionally, the inclinometer is carried by RNA.
[0018] Optionally, the inclinometer comprises an accelerometer.
[0019] Optionally, obtaining the yaw angle data includes measuring the yaw angle of the RNA using a magnetometer installed on the RNA.
[0020] Optionally, the yaw angle data is acquired by measuring a reference yaw angle of the RNA and then measuring a deviation between the yaw angle of the RNA and the reference yaw angle.
[0021] Optionally, the rotor rotates at a rotor frequency and the pitch angle varies at a frequency (IP) that occurs (changes) once per rotor revolution.
[0022] Another aspect of the present invention provides a wind turbine comprising: a tower; a rotor nacelle assembly (RNA) comprising a rotor and a nacelle, the rotor comprising one or more blades; and a control system configured to control the wind turbine by the method of the first aspect of the present invention.
[0023] Optionally, the control system comprises one or more sensors configured to generate measurement data, wherein the control system is configured to obtain the tilt angle data and the yaw angle data based on the measurement data.
[0024] Optionally, the one or more sensors comprise an inclinometer carried by the RNA.
[0025] Optionally, the inclinometer comprises an accelerometer.
[0026] Optionally, the one or more sensors comprise a magnetometer carried by the RNA. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Embodiments of the present invention will now be described with reference to the accompanying drawings, in which:
[0028] Figure 1 A wind turbine is illustrated.
[0029] Figure 2 A cross section of a nacelle of a wind turbine is schematically illustrated showing the main shaft, the gearbox and the electrical generator.
[0030] Figure 3 The tilt axis and yaw axis of the rotor are shown.
[0031] Figure 4 A control system for adjusting the blade pitch based on the pitch moment and the yaw moment is illustrated.
[0032] Figure 5a A two-line approximation of a side view of a tilted wind turbine tower is shown with an accelerometer sensor located on top of the tower.
[0033] Figure 5b The X, Y, and Z axes of the IMU are shown, as well as the tilt angle.
[0034] Figure 6 The diagram shows the RNA at two different yaw angles. DETAILED DESCRIPTION
[0035] Figure 1 An example of a wind turbine 1 is illustrated in a schematic perspective view. The wind turbine 1 includes a tower 2 and a rotor nacelle assembly (RNA) 7 located on top of the tower 2. The RNA 7 includes a nacelle 3 and a rotor 4, which is operably coupled to a generator housed in the nacelle 3. In addition to the generator, the nacelle 3 also houses various components required to convert wind energy into electrical energy, as well as various components required to operate, control and optimize the performance of the wind turbine 1.
[0036] The rotor 4 includes a central hub 5 and a plurality of blades 6 extending outwardly from the central hub 5. In the illustrated wind turbine 1, the rotor 4 includes three blades 6, but the number may vary. In addition, the wind turbine includes a control system. The control system may be placed in the nacelle or distributed in multiple locations inside (or outside) the turbine and communicated with.
[0037] When wind blows towards the wind turbine 1 , lift is generated, causing the rotor 4 to rotate, which in turn causes the generator in the nacelle 3 to generate electrical energy.
[0038] Figure 2 Various components inside the nacelle 3 are schematically illustrated. The nacelle 3 includes a nacelle frame 13, which structurally supports the nacelle 3 and the components inside the nacelle 3. The wind turbine 1 includes rotor blades 6, which are mechanically connected to the generator 9 through a gearbox 12. In direct drive systems and other systems, the gearbox 12 may not be present. The electricity generated by the generator 9 is injected into the grid through an electrical converter (not shown). The main shaft 11 is mechanically attached to the hub 5 at the front end. A bearing housing (not shown) is mechanically attached to the nacelle frame 13 and is configured to rotatably support the main shaft 11.
[0039] When blade 6 is around Figure 3 As the rotor planes 15 are shown sweeping, they experience changes in wind speed and direction. As a result, a tilt moment 60 is applied to the rotor about a horizontal tilt axis 61 and a yaw moment 62 is applied to the rotor about a yaw axis 63. The tilt axis 61 and the yaw axis 63 are perpendicular to each other. The moments 60, 62 are applied by the rotor to the main shaft 11.
[0040] Figure 4 Elements of a control system configured to control the wind turbine 1 are shown. The control system comprises a functional element 14 configured to run a load control algorithm to perform cyclic pitch actuation of the blades 6 based on the pitch moment data and the yaw moment data 16 .
[0041] The pitch of each blade is individually controlled by a respective blade pitch actuator 20A, 20B, 20C to reduce the magnitude of the pitch moment and the yaw moment of the wind turbine 1 .
[0042] The rotor 4 rotates at a rotor frequency (1P) and the pitch angle may vary once per revolution (1P) and / or twice per revolution (2P) and / or at a higher frequency than 2P. The phase of the pitch angle variation may vary from blade to blade.
[0043] It is recognised that there is a correlation between the tilt / yaw moment acting on the rotor 4 (which in turn is applied by the rotor 4 to the main shaft 11) and the tilt / yaw angle of the RNA 7, and that the tilt and yaw moment data 16 can be estimated based on the measured tilt and yaw angles of the RNA 7.
[0044] Figure 4 The control system is configured to acquire tilt angle data 24 indicating a tilt angle of the RNA 7 .
[0045] Figure 4 The control system is further configured to acquire yaw angle data 26 indicative of a yaw angle of the RNA 7 .
[0046] Figure 4 The control system is further configured to obtain a thrust 28 of the rotor 4. The thrust 28 may be an estimate of the rotor thrust given by a model 29 based on data collected from sensors on the wind turbine 1. The model 29 may be a model based on blade element momentum theory (BEM). Alternatively, the thrust 28 may be determined by other means.
[0047] Optionally, the tilt angle data 24 and / or the yaw angle data 26 are obtained by acquiring measurement data 32 and applying a signal filter (SF) 30 to the measurement data 32 to select 0P and 3P components. The measurement data 32 may include tilt angle measurement data 34 from a 3-axis accelerometer 50 of an inertial measurement unit (IMU) 51, and yaw angle measurement data 36 from a magnetometer 52 of the IMU 51.
[0048] The filter 30 may include a low pass filter (LPF) and a band pass filter (BPF). The LPF filters out high frequency components, leaving only steady state (0P) information. The BPF passes only the data of the required frequency, in this case the data of the 3P frequency.
[0049] This filtering method is only one example of a method that can be used to extract 0P and 3P information, and other methods are known to those skilled in the art.
[0050] The estimation method 38 is used to generate the tilt moment data and the yaw moment data 16. The moment data may be acquired in a fixed frame coordinate system of the wind turbine. In one embodiment, the entire turbine may be modeled using an offline simulator and a transfer function may be generated by a least squares estimation method. The estimation method 38 may then use the transfer function to map the yaw angle to the yaw moment, and to map the tilt angle and thrust to the tilt moment. Thus, the estimation method 38 is configured to determine the tilt moment data 44 based on the tilt angle data 24 and the thrust 28, and to determine the yaw moment data 46 based on the yaw angle data 26 (i.e., the thrust 28 is not required for the yaw moment determination).
[0051] The tilt moment data and yaw moment data 16 include tilt moment data 44 indicating the tilt moment acting on the rotor about the tilt axis and yaw moment data 46 indicating the yaw moment acting on the rotor about the yaw axis.
[0052] The control system is configured to control the pitch angle of one or more of the blades 6 based on the pitch moment data 44 and the yaw moment data 46. The blade pitch actuators 20A-C may control the pitch angle of the blades 6, each actuator individually controlling a respective one of the blades.
[0053] A controller (e.g., in the form of a proportional-integral (PI) controller 18) receives the tilt moment data and the yaw moment data 16 and uses a tilt reference setpoint M based on a proportional-integral control loop mechanism. tilt,ref The output is generated for the tilt moment data 44 and uses the yaw reference set point M yaw,ref An output is generated for yaw moment data 46 .
[0054] The inverse Coleman transform 40 is applied to the output of the PI controller 18 to generate a pitch reference signal θ for the actuator 20A. A,ref , pitch reference signal θ for actuator 20B B,ref and the pitch reference signal θ for actuator 20C C,ref .
[0055] The rotor rotates at the rotor frequency, once per revolution (i.e., 1P). The pitch angle of each blade can be changed at a frequency equal to or higher than the rotor frequency, specifically, at a frequency of 1P or 2P. That is, the pitch angle of the blade 6 can be actuated once or more per revolution to offset the asymmetric load acting on the rotor 4.
[0056] Now refer to Figure 5a and Figure 5b A method of acquiring tilt angle measurement data 34 is described. Figure 5a A tower bend is shown which is modelled as two rigid tower sections 2a, 2b coupled together. Figure 5a The total inclination angle (θ) of the tower 2 in FIG. 2 is θ1+θ2. The inclination angle (θ1) of the lower tower section 2a is the angle between the first line 47b defining the lower tower section 2a and the vertical line 47a, as shown in FIG. Figure 5a The inclination angle (θ2) of the upper tower section 2b is the angle between the line 47c defining the upper tower section 2b and the first line 47b. Therefore, the total inclination angle θ=θ1+θ2 can be approximated as the total inclination angle of the tower 2 relative to the vertical line 47a.
[0057] The IMU (here illustrated as an accelerometer 50) is positioned on the nacelle at the top of the tower 2, so the orientation angle of the IMU will change as the total tilt angle θ changes. Alternatively, an inclinometer mounted on the top of the tower 2 (rather than carried by the RNA 7) can be used to provide the tilt angle measurement data 34.
[0058] IMU's accelerometer 50 measurements Figure 5b The linear acceleration along the X, Y, and Z axes is shown in . This enables the IMU to operate as an inclinometer, estimating the RNA7's tilt angle θ relative to gravity as:
[0059]
[0060] in:
[0061] A y is the linear acceleration measured in the y direction of the IMU
[0062] A x is the linear acceleration measured in the x direction of the IMU
[0063] A z is the linear acceleration measured in the z direction of the IMU
[0064] The estimated tilt angle θ provides tilt angle measurement data 34 which is then filtered to provide 0P and 3P tilt angle data 24.
[0065] Now refer to Figure 6 Two different methods of obtaining yaw angle measurement data 36 are described.
[0066] Figure 6 A top view of the RNA 7 at two different yaw angles is shown. The difference between the two different angles is represented by the yaw angle (ψ). The IMU 51 is mounted at the rear of the nacelle 3.
[0067] In one approach, a 3-axis accelerometer of the IMU 51 may be used to measure linear acceleration along the X, Y, and Z axes, and these acceleration measurements are doubly integrated to give the yaw angle measurement data 36. Alternatively, the yaw angle measurement data 36 may be obtained by directly acquiring position data using one or more Global Positioning System (GPS) sensors.
[0068] In a second method, the magnetometer of the IMU 51 may be used to measure the orientation of the IMU 51 relative to the Earth's magnetic field, and this orientation is used to give the yaw angle measurement data 36 .
[0069] The yaw angle measurement data 36 can be obtained by measuring a reference yaw angle of the RNA and then measuring the deviation of the current yaw angle of the RNA from the reference yaw angle. The RNA 7 is driven by a yaw drive system (not shown) which rotates the RNA 7 to point into the wind and once the upwind position is reached the yaw drive system locks. The reference yaw angle can be measured at the moment when the yaw drive system initially locks.
[0070] When the yaw drive system is locked, a reference measurement result M is obtained. w：
[0071] Reference measurement results
[0072] Among them, M x 、M y and M zis the reference magnetic field measurement result in the X, Y, Z coordinate system of the magnetometer 52.
[0073] For the reference measurement, the reference yaw angle a relative to magnetic north is given by a=atan2(M z ,M x )
[0074] Then get the current measurement result N w :
[0075] Current measurement results
[0076] Where N x 、N y and N z is the current magnetic field measurement result in the X, Y, Z coordinate system of the magnetometer 52.
[0077] For the current measurement result, the current yaw angle b relative to the magnetic north direction is given by b=atan2(N z ,N x )
[0078] The difference between the yaw angles a and b gives the yaw drift:
[0079]
[0080] Yaw drift Y d Yaw angle measurement data 36 is provided, which after filtering provides 0P and 3P yaw angle data 26.
[0081] An advantage of the above method is that the measurement data 32 can be determined using one or more non-intrusive sensors (such as IMU 51). This allows Figure 4 The control system of the invention can determine the pitch moment data 44 and the yaw moment data 46 without the use of blade load sensors. The IMU 51 can be retrofitted to existing wind turbines without the need for invasive modifications (which would be necessary for blade load sensors).
[0082] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.
Claims
1. A method of controlling a wind turbine, the wind turbine comprising: Tower; and a rotor nacelle assembly (RNA) comprising a rotor and a nacelle, the rotor comprising one or more blades, the method comprising: acquiring tilt angle data indicating the tilt angle of the RNA; acquiring yaw angle data indicating the yaw angle of the RNA; obtaining the thrust of the rotor; determining a tilt moment data based on the tilt angle data and the thrust, wherein the tilt moment data indicates a tilt moment acting on the rotor about a tilt axis; determining yaw moment data based on the yaw angle data, wherein the yaw moment data is indicative of a yaw moment acting on the rotor about a yaw axis; and A pitch angle of one or more of the blades is controlled based on the pitch moment data and the yaw moment data.
2. The method according to claim 1, wherein: The tilt angle data and / or the yaw angle data are acquired by acquiring measurement data and applying a low pass filter and a band pass filter to the measurement data to select 0P and 3P components respectively.
3. A method according to any preceding claim, wherein: Acquiring the tilt angle data includes measuring the tilt of the RNA relative to gravity using an inclinometer, and determining the tilt angle data based on the measured tilt of the RNA.
4. The method according to claim 3, wherein: The inclinometer is carried by RNA.
5. The method according to claim 3 or 4, wherein: The inclinometer includes an accelerometer.
6. A method according to any preceding claim, wherein: Acquiring the yaw angle data includes measuring the yaw angle of the RNA using a magnetometer installed on the RNA.
7. A method according to any preceding claim, wherein: The yaw angle data is acquired by measuring a reference yaw angle of the RNA and then measuring a deviation between the yaw angle of the RNA and the reference yaw angle.
8. A method according to any preceding claim, wherein: The rotor rotates at a rotor frequency and the pitch angle varies at a frequency (IP) that occurs once per rotor revolution.
9. A wind turbine comprising: Tower; a rotor nacelle assembly (RNA) comprising a rotor and a nacelle, the rotor comprising one or more blades; and a control system configured to control a wind turbine by a method as claimed in any preceding claim.
10. The wind turbine according to claim 9, wherein: The control system comprises one or more sensors configured to generate measurement data, wherein the control system is configured to obtain the tilt angle data and the yaw angle data based on the measurement data.
11. A wind turbine according to claim 9 or 10, wherein: The one or more sensors include an inclinometer carried by the RNA.
12. The wind turbine according to claim 11, wherein: The inclinometer includes an accelerometer.
13. A wind turbine according to claim 10, 11 or 12, wherein: The one or more sensors include a magnetometer carried by RNA.