Determining a blade azimuth angle of a wind turbine
By using acceleration sensor signals in the wind turbine impeller hub to determine the reference impeller azimuth angle and generating a reset pulse signal to reset the impeller velocity integrator, the problems of cumulative error and sensor damage in impeller azimuth angle determination are solved, and accurate and reliable impeller position determination is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- VESTAS WIND SYSTEMS AS
- Filing Date
- 2024-12-13
- Publication Date
- 2026-07-24
Smart Images
Figure CN122459577A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to determining the azimuth angle of a wind turbine rotor. Specifically, a reference rotor azimuth angle is determined based on an acceleration sensor signal from an acceleration sensor located in the rotor hub of the wind turbine rotor, and this reference rotor azimuth angle is used to reset the rotor velocity integrator used to determine the rotor azimuth angle. Background Technology
[0002] A wind turbine typically comprises a tower, a nacelle located atop the tower to house one or more electrical components (such as a converter), an rotor that rotates relative to the nacelle and tower, and several rotor blades (usually three blades) attached to the rotor. The rotational position of the wind turbine rotor—also known as the rotor azimuth—is used for a variety of different functions / applications. These applications include positioning the rotor and blades during maintenance or repair operations of the wind turbine, calibrating other sensing systems on the wind turbine, and serving as input to one or more control programs / processes for the wind turbine, such as load shedding control programs. Therefore, it should be understood that obtaining an accurate determination of the wind turbine rotor azimuth is important.
[0003] One known method for obtaining the azimuth angle of a wind turbine rotor is to apply an integrator function / module to the obtained wind turbine rotor velocity signal, i.e., to integrate the obtained wind turbine rotor velocity with respect to time. The rotor velocity signal can be obtained in any suitable manner, such as based on a signal obtained from a rotary encoder that measures the generator speed of the wind turbine. This method is prone to capturing any errors in the rotor velocity measurement, which accumulate over time.
[0004] One known method to mitigate these accumulated errors is to include a dedicated reset sensor in the wind turbine to sense when the turbine rotor begins a new rotation. Once this is sensed, a signal is generated to reset the integrator, minimizing the accumulated errors. A drawback of this method is that the dedicated sensor may not reliably detect the target magnet protruding from the rotor's locking disc, thus failing to accurately measure when the rotor begins a new rotation. To address this, the sensor could be moved closer to the rotor locking disc; however, this could cause the magnet and sensor to collide under uneven loads on the rotor, potentially damaging or even destroying the magnet and / or the sensor.
[0005] There remains a need for improved methods to obtain impeller azimuth velocity in an accurate and reliable manner. This invention is proposed in this context. Summary of the Invention
[0006] According to one aspect of the present invention, a method for determining the azimuth angle of a wind turbine rotor is provided. The method includes obtaining a rotor speed signal indicating the speed of the wind turbine rotor. This rotor speed signal is used as input to a rotor speed integrator. The method includes receiving an acceleration sensor signal from an acceleration sensor located in the rotor hub of the wind turbine, the signal indicating acceleration of the rotor hub in the radial direction relative to the rotor hub's axis of rotation due to gravity. The method includes determining a reference rotor azimuth angle based on the received acceleration sensor signal. The method includes generating a reset pulse signal based on the determined reference rotor azimuth angle. The method includes resetting the rotor speed integrator upon receiving the generated reset pulse signal at the rotor speed integrator. The method includes using the reset rotor speed integrator to determine the rotor azimuth angle of the wind turbine based on the obtained rotor speed signal.
[0007] A reset pulse signal can be generated when the determined reference impeller azimuth angle meets the specified conditions indicating that the wind turbine impeller is in a specified rotational position. This specified rotational position may correspond to a (specific) impeller blade of the wind turbine pointing substantially directly downwards. This rotational position may correspond to an impeller azimuth angle of zero radians.
[0008] The specified rotational position can correspond to the minimum value of the reference impeller azimuth angle. The specified condition can be that the defined reference impeller azimuth angle drops below a specified threshold greater than the minimum value. Typically, the minimum value can be zero radians (and can correspond to one of the wind turbine impeller blades pointing directly downwards). Therefore, the specified threshold can be a value only slightly greater than the minimum value, for example, only slightly greater than zero radians. For example, the specified threshold can therefore be any value less than or equal to 0.1 radians, less than or equal to 0.2 radians, less than or equal to 0.3 radians, etc., or any other suitable value.
[0009] In some examples, resetting the impeller velocity integrator may include setting the instantaneous impeller azimuth angle in the impeller velocity integrator to be equal to the reference impeller azimuth angle. Resetting the impeller velocity integrator can be viewed as restarting the integrator calculation from zero, where the value represents the impeller's phase / position.
[0010] The reset pulse signal is generated once for each revolution of the impeller.
[0011] The received acceleration sensor signal can indicate the acceleration of the impeller hub due to gravity in the first and second mutually orthogonal radial directions.
[0012] In some examples, determining the reference impeller azimuth angle may include applying trigonometric functions to the components of the received accelerometer signal in the first and second mutually orthogonal radial directions.
[0013] The reference impeller azimuth angle can be determined based on the orientation and position of the accelerometer in the impeller hub.
[0014] This method may include applying an offset to the received accelerometer signal to compensate for contributions from centrifugal force or centripetal acceleration. This offset may be proportional to the square of the impeller velocity or impeller angular velocity in the obtained impeller velocity signal. A reference impeller azimuth angle may be determined based on the centrifugally compensated or centripetally compensated accelerometer signal.
[0015] This offset can be applied to the transformed components of the accelerometer signal, that is, the accelerometer signal that has been transformed from a rotating reference frame to a stationary reference frame.
[0016] The rotor speed in the obtained rotor speed signal can be determined based on the received generator speed signal, which indicates the speed of the wind turbine's generator. The generator speed signal can be received from the wind turbine's rotary encoder.
[0017] The rotor speed in the obtained rotor speed signal can be determined as the generator speed after gear ratio compensation via the wind turbine gearbox.
[0018] The impeller velocity in the obtained impeller velocity signal can be determined by performing the following steps: receiving an angular velocity sensor signal indicating the angular velocity of the impeller hub from an angular velocity sensor located in the impeller hub of the wind turbine; determining a first estimated rotational velocity of the impeller hub based on the received angular velocity sensor signal; determining a second estimated rotational velocity of the impeller hub based on the received acceleration sensor signal; determining a correction value based on the difference between the first and second estimated rotational velocities; and applying the correction value to the first estimated rotational velocity to determine the impeller velocity of the wind turbine.
[0019] According to another aspect of the invention, a non-transitory computer-readable storage medium is provided that stores instructions which, when executed by one or more processors, cause the one or more processors to perform the method as defined above.
[0020] According to another aspect of the invention, a controller is provided for determining the azimuth angle of a wind turbine rotor. The controller is configured to acquire a rotor speed signal indicating the speed of the wind turbine rotor. This rotor speed signal is input to a rotor speed integrator. The controller is configured to receive acceleration sensor data from an acceleration sensor located in the rotor hub of the wind turbine, the data indicating acceleration in the radial direction of the rotor hub relative to the rotor hub's axis of rotation due to gravity. The controller is configured to determine a reference rotor azimuth angle based on the received acceleration sensor data. The controller is configured to generate a reset pulse signal based on the determined reference rotor azimuth angle. The controller is configured to reset the rotor speed integrator upon receiving the generated reset pulse signal at the rotor speed integrator. The controller is configured to use the reset rotor speed integrator to determine the rotor azimuth angle of the wind turbine based on the acquired rotor speed signal.
[0021] According to another aspect of the invention, a wind turbine including a controller as defined above is provided. Attached Figure Description
[0022] Examples of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of a wind turbine according to an example of the present invention; Figure 2 An example according to the present invention is illustrated schematically. Figure 1 The controller of the wind turbine shown; Figure 3 The example shown is derived from the present invention. Figure 2 The steps of the method executed by the controller shown; Figure 4 schematically shown Figure 1 The impeller plane of the wind turbine shown, and Figure 1 The example location of the accelerometer in the hub of a wind turbine impeller is shown. Figure 5 Is using Figure 3 The method determined Figure 1 A graph showing the change of the impeller position of a wind turbine over time, compared with impeller positions obtained using previously known methods; and, Figure 6 Is using Figure 3 The method generates a graph of the impeller integrator reset pulse over time and compares it with the impeller integrator reset pulse generated according to a previously known method. Detailed Implementation
[0023] Figure 1An example of a wind turbine 10 is illustrated schematically. The wind turbine 10 includes a tower 102, a nacelle 103 disposed at the apex or top of the tower 102, and an impeller 104 operatively coupled to a generator housed within the nacelle 103. In addition to the generator, the nacelle 103 also houses other components necessary for converting wind energy into electrical energy, as well as various components required for operating, controlling, and optimizing the performance of the wind turbine 10. The impeller 104 of the wind turbine 10 includes a central hub 105 and three impeller blades 106 projecting outward from the central hub 105.
[0024] Impeller 104 and impeller blades 106 rotate about the impeller axis and define the impeller plane. In particular, wind impacting the impeller blades 106 drives the impeller 104 and impeller blades 106 to rotate, thereby capturing wind energy that can be converted into electrical energy, for example, for supplying to the power grid.
[0025] The wind turbine 10 includes an acceleration sensor, in the form of an accelerometer 107 located in the rotor hub 105. In the example described, the accelerometer 107 is a triaxial accelerometer configured to detect acceleration of the rotor hub in three mutually orthogonal directions. The orientation and position of the accelerometer 107 within (or relative to) the rotor hub 105 will be known. The accelerometer 107 may be part of a sensing device / (inertial) measurement unit that includes further sensors. For example, such a measurement unit may additionally include a (triaxial) gyroscope configured to measure the angular motion / velocity of the rotor hub 105.
[0026] This invention provides a method and controller for accurately and reliably determining the rotational position (hereinafter referred to as the rotor azimuth) of a wind turbine rotor 104. An advantage of this invention is that it provides accurate and reliable determination of the rotor azimuth without requiring a dedicated reset sensor to reset the rotor velocity integrator used to determine the rotor azimuth. This invention advantageously utilizes existing hardware of the wind turbine—namely, the accelerometer 107 in the rotor hub 105—to determine when to reset the rotor velocity integrator. Eliminating the need for a dedicated reset sensor reduces the electrical and mechanical complexity of achieving rotor azimuth determination, which in turn reduces component costs, maintenance costs / time, and frees up space in the rotor hub. The method of this invention is more reliable than previous methods using dedicated reset sensors because it eliminates the risk of said sensor being damaged / destroyed. Further advantages related to this invention will become apparent below.
[0027] Figure 2The controller 20 of the wind turbine 10 is schematically shown. The controller 20 is used to determine the azimuth angle of the wind turbine rotor 104. The determined rotor azimuth angle can be used for any suitable purpose. For example, the determined rotor azimuth angle can be used to position the rotor and rotor blades during maintenance or repair operations of the wind turbine, to calibrate other sensing systems of the wind turbine, and as input to one or more control programs / processes of the wind turbine, such as load shedding control programs. The controller 20 can be placed inside the rotor hub 105, in the nacelle 103, in the tower 102, or distributed in several locations inside (or outside) the turbine 10 and communicate with each other.
[0028] The controller 20 is configured to receive a measured / determined rotor speed signal 201, indicating the (rotational) speed of the wind turbine rotor 104. The rotor speed signal 201 can be obtained from any suitable source. The rotor speed signal can be determined based on a measured generator speed of the wind turbine 10. The wind turbine 10 can be equipped with a rotary encoder configured to measure the generator speed. The rotor speed can then be subsequently determined as the measured generator speed divided by the gearbox speed ratio of the wind turbine 10 (the generator speed after gear ratio compensation). This can be considered a particularly accurate method for obtaining the rotor speed signal 201.
[0029] Another method for determining the impeller velocity can be based solely on sensor signals obtained from the inertial measurement unit of the wind turbine 10, particularly from the accelerometer 107 and the gyroscope. Specifically, a first estimated rotational velocity of the impeller hub 105 can be determined based on the angular velocity signal from the gyroscope, and a second estimated rotational velocity of the impeller hub 105 can be determined based on the acceleration signal from the accelerometer 107. A correction value can be determined based on the difference between the first and second estimated impeller velocities, and the impeller velocity is determined by applying the correction to the first estimated impeller velocity. This method can be considered as providing a reliable and accurate impeller velocity measurement that is robust to external noise.
[0030] In some examples, controller 20 may include an impeller speed selector module. In such examples, controller 20 may be configured to receive more than one impeller speed signal, particularly from different sources / obtained through different methods (e.g., the methods described above). The selector module may then be configured to select which of the received impeller speed signals will be used by other modules of controller 20 to determine the impeller azimuth angle (as described below). Advantageously, if no impeller speed signal is received from one source (e.g., due to a fault), the impeller speed selector module can select another source to provide the impeller speed signal to ensure continued operation of controller 20. In some examples, the impeller speed selector module may combine impeller speed measurements / estimates from multiple sources to obtain an impeller speed signal used by controller 20 to determine the impeller azimuth angle, which can increase the accuracy of the determination.
[0031] The impeller speed signal 201 is input to the integrator module 202 of the controller 20. The integrator 202 is configured to integrate the received impeller speed signal 201 with respect to time to obtain the impeller azimuth angle signal 203. The integrator module 202 can be any suitable functional control module, such as a proportional-integral (PI) controller or a proportional-integral-derivative (PID) controller.
[0032] As described above, due to the cumulative error of the impeller speed signal, the integrator 202 may drift away from the correct / accurate impeller azimuth angle determination. To address this issue, a reset signal can be generated to reset the integrator 202 at the start of each (new) rotation of the impeller 104, meaning that the error will not accumulate over multiple rotations of the impeller 104. To achieve this, the controller 20 includes a reset estimation unit / module 204 for determining when to reset the integrator 202, i.e., at the start of a new rotation of the impeller 104. When unit 204 determines that the integrator 202 will be reset, a reset signal 205 is generated and sent to the integrator 204 to reset the integrator 202. It is important to accurately determine when the impeller begins a new rotation so that the reset signal can be generated at the appropriate time.
[0033] As described above, in previous methods, this reset signal could be generated based on the output of a dedicated reset sensor. However, in this example, the reset estimation unit 204 is configured to receive an acceleration signal 206 from an accelerometer 107 in the impeller hub 105 and to generate a reset pulse signal 205 based on the received acceleration signal 107. This will be described in more detail below.
[0034] Figure 3The steps of a method 30, executed by controller 20, to determine the rotor azimuth angle of wind turbine 10 are shown. In step 301, method 30 involves obtaining a rotor speed signal 201 indicating the rotor speed of wind turbine 10. As described above, the rotor speed signal can be obtained from any suitable source and is used to input into rotor speed integrator 202.
[0035] In step 302, method 30 involves receiving an acceleration sensor signal 206 from an acceleration sensor 107 located in the wind turbine impeller hub 105. The acceleration signal 206 indicates the acceleration of the impeller hub 105 in the radial direction relative to the axis of rotation of the impeller hub 105 due to gravity. In this example, it is desirable to obtain the acceleration in two mutually orthogonal directions in the impeller plane (i.e., the radial direction relative to the impeller axis), as this will subsequently be used to determine an indication of the impeller azimuth angle. The estimation unit 204 can perform a coordinate transformation of the acceleration signal 206 from a rotating reference frame to a stationary reference frame to obtain the mutually orthogonal directions in the impeller plane. Therefore, one or more components of the acceleration sensor signal 206 can be transformed from a rotating reference frame rotating with the impeller 104 to a stationary reference frame.
[0036] It is particularly desirable to obtain the acceleration caused by gravity in two mutually orthogonal directions. The accelerometer 107 in the impeller hub 105 is primarily excited by gravity; however, the acceleration signal 206 will also include contributions due to centrifugal force, impeller rotational speed acceleration, and vibrations of the impeller hub 105 and nacelle 103. Method 30 may involve steps to compensate for (or remove) the centrifugal force contribution in the acceleration signal 206. This can be performed by the estimation unit 204 of the controller 20.
[0037] In the two measuring axes (i.e., two mutually orthogonal axes in the impeller plane) of the accelerometer 107 perpendicular to the main shaft of the impeller 104, the centrifugal force contribution causes an offset in the acceleration signal 206 that is proportional to the square of the impeller hub velocity. Therefore, method 30 may include the step of applying an offset to the received accelerometer signal 206 to compensate for the centrifugal force contribution contained therein. Specifically, the offset may be proportional to the square of the impeller velocity in the obtained impeller velocity signal 201, in which case the impeller velocity signal 201 is received by the estimation unit 204, such as... Figure 2 As shown.
[0038] refer to Figure 4 This paper describes a method for determining an offset applied to a received acceleration signal 206 to compensate for the contribution of centrifugal force in the signal 206. The offset is determined based on the (known) position and orientation of the accelerometer 107 relative to the axis of rotation in the impeller hub 105. Figure 4 The impeller plane 401 of the wind turbine 10 is schematically shown. Specifically, Figure 4 The impeller plane 401 is shown when a (specific) impeller blade 106 points directly downward, which corresponds to an impeller azimuth angle θ of zero radians, i.e., θ=0.
[0039] Figure 4 The two possible positions A and A' of the accelerometer 107 are schematically shown. n At position A, the accelerometer 107 is directly below (vertically downwards) the impeller axis 402 (i.e., the center of the impeller plane 401), that is, on the centerline 403 of the impeller plane 401, at a distance r from the center 402 of the impeller plane 401. a On the other hand, at position A n Accelerometer 107 deviates from the center line by an angle θ of 403 degrees. off And located at a distance of 402 from the center, a distance of r n Place, such as Figure 4 As shown. Note θ at position A. off =0. For example... Figure 4 As shown, the positioning of accelerometer 107 will affect the capture of centrifugal force F on the accelerometer axis. c The accelerometer 107 measures the acceleration in mutually orthogonal directions x and y (and parallel to the impeller axis in the z direction) in the impeller plane 401. Here, the measured acceleration The sensor signal 206 is transformed from a rotating reference frame to a stationary reference frame.
[0040] Offset angle θ off It can be determined as θ off = tan -1 (d x / d y ), where d x d y This is the known distance of accelerometer 107 from the center 402 of the impeller plane in the x and y directions. Radius r n identified as In addition, centrifugal force F c Subsequently identified as Where v rot The impeller angular velocity, and the centrifugal force components along the accelerometer axes x and y (e.g., in a stationary frame) will be F. c sinθ off and F c cosθ offFor convenience, the mass is considered as one in the above formula. These components can then be removed from the total measurements of the accelerometer 107 along their respective axes, thereby providing a centrifugal force offset to the received accelerometer signal 206.
[0041] In practice, the accelerometer 107 is affected by centripetal acceleration (and additional accelerations, such as gravity) and can measure centripetal acceleration. The centripetal acceleration measured by the accelerometer is determined by ω. 2 ·rn is given, where ω is the angular velocity. Therefore, accelerometer 107 may not be measuring F. c Instead, it is with F c The associated centripetal acceleration. The centripetal acceleration component measured along the accelerometer axis corresponds to the centrifugal force F. c The amount.
[0042] Therefore, instead of directly using the measurements from accelerometer 107, the mounting position and orientation of accelerometer 107 can be arbitrarily chosen by mapping sensor signal 206 to the stationary impeller coordinate system and then applying centrifugal force compensation or centripetal acceleration compensation. Thus, the mounting position of the accelerometer in the hub can be selected based on providing the simplest installation location.
[0043] Other disturbances in the received acceleration signal 206, such as those caused by vibrations of the impeller hub 105 and nacelle 103, are negligible because they have no sustained effect on the acceleration signal 206 and are insignificant in amplitude relative to the contribution from gravity in any case. Therefore, the resulting acceleration signal consists of two components with a 90-degree phase difference, providing a sinusoidal signal with an amplitude close to 1G and a frequency proportional to the impeller hub velocity.
[0044] Back Figure 3 In step 303, method 30 involves determining a reference impeller azimuth angle at the estimation unit 204 of the controller 20 based on the received acceleration sensor signal 206. This can be achieved by analyzing the mutually orthogonal components of the acceleration signal 206 in the impeller plane 401. (or the offset component of centrifugal force has been compensated) This is achieved using the arctangent function. This operation takes into account the sign of the axis / components to obtain results in the range of -π / 2 to π / 2, and this can be further transformed to the range of 0 to 2π. Further offsets can be applied to ensure that the reference impeller azimuth is obtained in the correct quadrant of the impeller plane 401.
[0045] In step 304, method 30 involves generating a reset pulse signal 205 at estimation unit 204 based on a determined reference impeller azimuth angle. In the example described, estimation unit 204 generates reset signal 205 when the determined reference impeller azimuth angle is zero, corresponding to a (specific) impeller blade 106 pointing directly downwards. More generally, reset signal 205 can be generated when the determined reference impeller azimuth angle satisfies predetermined conditions indicating that impeller 104 is in a specific rotational position. When operating within the range of 0 to 2π, the determined reference impeller azimuth angle monotonically increases from zero (when a specific impeller blade 106 points downwards) to 2π over one full rotation of impeller 104. The reference impeller azimuth angle then momentarily returns to zero at the start of the next impeller rotation.
[0046] The acceleration signal 206 can be sampled at the sampling rate of the controller 20, and a reference impeller azimuth angle can be determined at each sampling point. Depending on when the acceleration signal 206 is sampled, the determined reference impeller azimuth angle may not be exactly zero at any given sampling point when the impeller 104 completes one revolution and begins the next. To ensure that a reset pulse signal 205 is still generated at the start of a new impeller cycle, in some examples, the estimation unit 204 can be configured to generate the reset pulse signal 205 when the determined reference impeller azimuth angle changes from above a defined threshold close to zero to below a defined threshold. This captures the moment when the impeller 104 completes one revolution (at which point the reference impeller azimuth angle determined at the sampling point is close to 2π) and begins the next revolution (at which point the reference impeller azimuth angle determined at subsequent sampling points may be slightly greater than zero). The threshold can be defined as needed, for example, based on the sampling rate. As an indicative example only, the threshold can be set to one of 0.1 radians, 0.2 radians, 0.3 radians, etc.; however, it should be understood that any suitable value can be used for this purpose.
[0047] In step 305, method 30 involves resetting the impeller speed integrator 202 when a reset pulse signal 205 generated by the estimation unit 204 is received at the impeller speed integrator 202. In some examples, resetting the impeller speed integrator 202 can be considered as setting the instantaneous impeller azimuth angle in the impeller speed integrator 202 to be equal to the reference impeller azimuth angle, for example, zero. Resetting the impeller speed integrator can be considered as resetting the calculation of integrator 202 to zero in order to clear the accumulated error of the output of integrator 202 (i.e., the impeller azimuth angle). In the example described, integrator 202 is reset for each revolution of impeller 104, meaning that any error from the impeller speed signal 201 in integrator 202 only accumulates for one revolution of impeller 104. In different examples, the reset pulse signal 205 can be generated at a higher or lower frequency than per revolution of impeller as needed.
[0048] In step 306, method 30 then involves using a reset impeller speed integrator 202 to determine the impeller azimuth angle 203 of the wind turbine 10 based on the obtained impeller speed signal 201.
[0049] It should be noted that while it is advantageous to use a reference impeller azimuth angle determined based on the impeller hub accelerometer 107 to generate a reset pulse for the impeller speed integrator 202, it is still advantageous to determine the impeller azimuth angle based on the obtained impeller speed signal 201, for example, as an input to one or more control programs of the wind turbine. This is because vibrations of the wind turbine 10 (e.g., lateral vibrations of the tower 102) can affect the accuracy of the reference impeller azimuth angle determined based on the acceleration signal 206. For example, discontinuities may appear in the signal when the impeller blades 106 pass over the tower 102. On the other hand, impeller speed measurements are not affected by tower vibrations, so the integration of the impeller speed signal can be used without any discontinuities.
[0050] Figure 5 and Figure 6 The comparison results of the method of the present invention with the aforementioned known methods for determining the impeller azimuth angle when using a dedicated reset sensor are shown. In particular, Figure 5 A graph showing the impeller position as a function of time is displayed, with the impeller position determined according to the present invention shown as a solid line, and the impeller position determined according to a previous method using a dedicated azimuth sensor shown as a dashed line. It can be seen that the impeller position (impeller azimuth angle) increases monotonically from zero to 2π, and then drops back to zero essentially instantaneously at the start of a new impeller revolution. It can also be seen that the impeller position determined using the present invention is almost indistinguishable from that of previously known methods.
[0051] Figure 6 The diagram shows the generated reset pulse as a function of time, and specifically includes a first graph 601 illustrating the reset pulse generated according to the present invention and a second graph 602 illustrating the reset pulse generated according to a prior method using a dedicated reset sensor. The time difference between the two reset pulses 601 and 602 is within a few sampling points. The method of the present invention provides a reset pulse that is at least as accurate as a prior solution, while being more reliable and cost-effective.
[0052] Many modifications may be made to the examples without departing from the scope of the appended claims.
[0053] The controller 20 can take the form of any suitable computing device, such as one or more functional units or modules implemented on one or more computer processors. Such functional units can be provided using conventional or custom processors and memory, with suitable software running on any suitable computing substrate. One or more functional units can use a common computing substrate (e.g., they can run on the same server) or separate substrates, or one or two functional units themselves can be distributed among multiple computing devices. The computer memory can store instructions for performing methods executed by the controller, and the processor can execute the stored instructions to perform the methods.
Claims
1. A method for determining the azimuth angle of a wind turbine rotor, the method comprising: Obtain an impeller speed signal indicating the speed of the wind turbine impeller, the impeller speed signal being input into an impeller speed integrator; Acceleration sensor signals are received from an acceleration sensor located in the hub of a wind turbine impeller, the signals indicating the acceleration in the radial direction of the impeller hub relative to the axis of rotation of the impeller hub due to gravity; The reference impeller azimuth angle is determined based on the received acceleration sensor signal; A reset pulse signal is generated based on the determined reference impeller azimuth angle; When the generated reset pulse signal is received at the impeller speed integrator, the impeller speed integrator is reset. as well as The rotor azimuth angle of the wind turbine is determined based on the obtained rotor velocity signal using a reset rotor velocity integrator.
2. The method according to claim 1, wherein a reset pulse signal is generated when the determined reference impeller azimuth angle satisfies the specified condition indicating that the wind turbine impeller is in a specified rotational position.
3. The method of claim 2, wherein the specified rotational position corresponds to the minimum value of the reference impeller azimuth angle, and wherein the specified condition is that the determined reference impeller azimuth angle drops below a specified threshold greater than the minimum value.
4. The method according to any one of the preceding claims, wherein resetting the impeller velocity integrator comprises setting the instantaneous impeller azimuth angle in the impeller velocity integrator to be equal to the reference impeller azimuth angle.
5. The method according to any one of the preceding claims, wherein the reset pulse signal is generated once for each revolution of the impeller.
6. The method according to any one of the preceding claims, wherein the received acceleration sensor signal indicates the acceleration of the impeller hub due to gravity in the first and second mutually orthogonal radial directions.
7. The method of claim 6, wherein determining the reference impeller azimuth angle comprises applying trigonometric functions to the components of the received acceleration sensor signal in the first and second mutually orthogonal radial directions.
8. The method of claim 7, wherein the reference impeller azimuth angle is determined based on the orientation and position of the accelerometer in the impeller hub.
9. The method according to any one of the preceding claims, the method comprising applying an offset to a received accelerometer signal to compensate for a centrifugal force contribution therein, wherein the offset is proportional to the square of the impeller velocity in the obtained impeller velocity signal, and wherein a reference impeller azimuth angle is determined based on the centrifugally compensated accelerometer signal.
10. The method according to any one of the preceding claims, wherein the impeller speed in the obtained impeller speed signal is determined based on a received generator speed signal indicating the generator speed of the wind turbine.
11. The method of claim 10, wherein the impeller speed in the obtained impeller speed signal is determined as the generator speed after gear ratio compensation via the wind turbine gearbox.
12. The method according to any one of claims 1 to 9, wherein the impeller velocity in the obtained impeller velocity signal is determined by: Receive angular velocity sensor signals indicating the angular velocity of the wind turbine hub from an angular velocity sensor located in the wind turbine rotor hub; The first estimated rotational speed of the impeller hub is determined based on the received angular velocity sensor signal; The second estimated rotational speed of the impeller hub is determined based on the received acceleration sensor signal; The correction value is determined based on the difference between the first and second estimated rotational speeds; as well as The correction value is applied to the first estimated rotational speed to determine the impeller speed of the wind turbine.
13. The method according to any one of the preceding claims further includes performing a coordinate transformation of the components of the accelerometer signal (206) from a rotating reference frame to a stationary reference frame.
14. A non-transitory computer-readable storage medium having instructions stored thereon that, when executed by one or more processors, cause the one or more processors to perform the method according to any one of the preceding claims.
15. A controller for determining the azimuth angle of a wind turbine rotor, the controller being configured to: Obtain an impeller speed signal indicating the speed of the wind turbine impeller, the impeller speed signal being input into an impeller speed integrator; Acceleration sensor data is received from an acceleration sensor located in the hub of a wind turbine impeller, the data indicating the acceleration of the impeller hub in the radial direction relative to the axis of rotation of the impeller hub due to gravity; The reference impeller azimuth angle is determined based on the received acceleration sensor data; A reset pulse signal is generated based on the determined reference impeller azimuth angle; When the generated reset pulse signal is received at the impeller speed integrator, the impeller speed integrator is reset. as well as The rotor azimuth angle of the wind turbine is determined based on the obtained rotor velocity signal using a reset rotor velocity integrator.
16. A wind turbine comprising the controller according to claim 15.