System and method for monitoring wind turbine pitch bearing

Abstract

A system and method for monitoring a pitch system of a wind turbine includes monitoring at least one electrical state of the pitch system via one or more first sensors. The method also includes monitoring at least one mechanical state of the pitch system via one or more second sensors. Further, the method includes receiving, via a controller communicatively coupled to the one or more first sensors and second sensors, sensor signals representative of the at least one electrical state and the at least one mechanical state of the pitch system. Accordingly, the method includes determining, via the controller, a bearing state of a pitch bearing of the pitch system based on the at least one electrical state and the at least one mechanical state of the pitch system.

Description

Technical Field

[0001] This topic generally relates to wind turbines, and more specifically to systems and methods for monitoring wind turbine pitch bearings. Background Technology

[0002] Wind power is considered one of the cleanest and most environmentally friendly currently available energy sources, and wind turbines are receiving increasing attention in this regard. Modern wind turbines typically consist of a tower, a generator, an optional gearbox, a nacelle, and one or more rotor blades. The rotor blades extract kinetic energy from the wind using the known airfoil principle and transfer this kinetic energy via rotational energy to rotate a shaft that connects the rotor blades to the gearbox, or, if no gearbox is used, directly to the generator. The generator then converts the mechanical energy into electrical energy, which can be fed into the public power grid.

[0003] To correctly orient the nacelle and rotor blades relative to wind direction, wind turbines typically include one or more yaw and / or pitch bearings. Therefore, yaw and / or pitch bearings are used to safely operate wind turbines in a variety of wind conditions and to extract maximum power output for a given wind condition. Yaw and / or pitch bearings are typically slewing bearings, which are rotating roller element bearings that typically support heavy but slowly rotating or slowly oscillating loads. Thus, the yaw bearing allows rotation of the nacelle and is mounted between the tower and the nacelle, while the pitch bearing allows rotation of the rotor blades and is mounted between a rotatable hub and one of the rotor blades. A typical yaw and / or pitch bearing consists of an outer ring and an inner ring, with multiple roller elements (e.g., ball bearings) constructed between the rings.

[0004] As wind turbines continue to increase in size, slewing bearings must also increase in size due to the increased load. Furthermore, in order for slewing bearings to withstand this load, they must include various components that adequately respond to the increased load. Therefore, conventional bearings, for example, typically include spacers between each roller element to maintain a uniform load throughout the bearing.

[0005] Wind turbine pitch bearings experience a variety of combined loads and pitch profiles. This operational characteristic leads to bearing fatigue and fretting damage, as well as ball repositioning issues. Because field wind conditions are inherently random, accurately predicting the movement of rolling elements is increasingly difficult, and such prediction is crucial for understanding various bearing failure modes. For example, in some pitch bearings, the convergence of rolling elements can apply additional loads or stresses to the bearing cage. Eventually, the cage may break into fragments and may no longer be effective in separating the rolling elements and maintaining their spatial constancy. Furthermore, these damaged cage fragments can be further pushed away from the raceways and even out of the bearing rings.

[0006] The inspection and repair process for pitch bearings can be complex and time-consuming if not scheduled promptly. Furthermore, these bearings are often expensive and may be difficult to access and replace. Therefore, failure of such bearings can lead to lengthy and costly repair processes. Repair and maintenance processes can be significantly improved, and downtime and associated losses can be minimized, if monitoring technologies that provide early warnings about the bearing's condition were available.

[0007] Therefore, improved systems and methods for monitoring the yaw and pitch bearings of wind turbines will be welcomed in the field to provide early warnings about bearing condition. This would significantly improve repair and maintenance processes and minimize downtime and associated losses. Summary of the Invention

[0008] Aspects and advantages of the invention will be set forth in the following description, or may be apparent from the description, or may be understood by practice of the invention.

[0009] On one hand, this disclosure relates to a method for monitoring a pitch system of a wind turbine. The pitch system has at least one pitch bearing. The method includes monitoring at least one electrical state of the pitch system via one or more first sensors. The method also includes monitoring at least one mechanical state of the pitch system via one or more second sensors. Furthermore, the method includes receiving sensor signals representing at least one electrical state and at least one mechanical state of the pitch system via a controller communicatively coupled to the one or more first and second sensors. Therefore, the method includes determining the bearing state of the pitch bearing via the controller based on at least one electrical state and at least one mechanical state of the pitch system.

[0010] On the other hand, this disclosure relates to a wind turbine. The wind turbine includes a tower, a nacelle mounted on top of the tower, and a rotor having a rotor and a rotatable hub mounted thereto. The rotatable hub has at least one rotor blade mounted thereto via a pitch system. The pitch system includes a pitch bearing communicatively connected to a pitch controller. The pitch controller includes a monitoring system for monitoring the pitch bearing. More specifically, the monitoring system includes at least one first sensor for monitoring at least one electrical state of the pitch system, at least one second sensor for monitoring at least one mechanical state of the pitch system, and a controller communicatively connected to the first and second sensors. Furthermore, the controller is configured to receive sensor signals from the first and second sensors and determine the bearing state of the pitch bearing based on the electrical and mechanical states of the pitch system.

[0011] In another aspect, this disclosure relates to a monitoring system for a bearing system of a wind turbine. The monitoring system includes at least one first sensor for monitoring at least one electrical state of the bearing system, at least one second sensor for monitoring at least one mechanical state of the bearing system, and a controller communicatively connected to the at least one first sensor and the second sensor. Therefore, the controller is configured to receive sensor signals from the first and second sensors and determine the bearing state of the bearing system based on at least one electrical state and at least one mechanical state of the bearing system. In one embodiment, the bearing system may include a pitch bearing or a yaw bearing of the wind turbine.

[0012] It should be understood that the monitoring system may also include any combination of the features and / or embodiments described herein.

[0013] These and other features, aspects, and advantages of the invention will be further supported and described with reference to the following description. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0014] Technical Solution 1. A method for monitoring a pitch system of a wind turbine, the pitch system having at least a pitch bearing, the method comprising: At least one electrical state of the pitch system is monitored via one or more first sensors; At least one mechanical state of the pitch system is monitored via one or more second sensors; and A controller communicatively connected to the one or more first and second sensors receives sensor signals representing at least one electrical state and at least one mechanical state of the pitch system; and The controller determines the bearing condition of the pitch bearing based on at least one electrical state and at least one mechanical state of the pitch system.

[0015] Technical Solution 2. The method according to Technical Solution 1, wherein the at least one electrical state includes at least one of pitch motor current, pitch motor voltage, torque, expected pitch angle from pitch analyzer model, or one or more pitch control signals.

[0016] Technical Solution 3. The method according to Technical Solution 1, wherein the at least one mechanical state includes at least one of pitch angle, pitch speed, or pitch rotor spin speed.

[0017] Technical Solution 4. The method according to Technical Solution 1 further includes monitoring the wind speed of the wind turbine, and determining the bearing condition of the pitch bearing based on the at least one electrical state, the at least one mechanical state of the pitch system, and the wind speed.

[0018] Technical Solution 5. The method according to Technical Solution 1, wherein determining the bearing state of the pitch bearing based on the at least one electrical state and the at least one mechanical state of the pitch system further includes: A quantitative relationship is derived between the at least one electrical state and the at least one mechanical state of the pitch system.

[0019] Technical Solution 6. The method according to Technical Solution 5 further includes deriving a quantitative relationship between the at least one electrical state and the at least one mechanical state of the pitch system from a physical three-axis pitch controller model.

[0020] Technical Solution 7. The method according to Technical Solution 1, wherein determining the bearing state of the pitch bearing based on the at least one electrical state and the at least one mechanical state of the pitch system further includes: One or more fault indicators are used to determine the at least one electrical state and the at least one mechanical state of the pitch system.

[0021] Technical Solution 8. The method according to Technical Solution 7, wherein determining the one or more fault indicators for the at least one electrical state and the at least one mechanical state of the pitch system further includes: Analyze the defect characteristic trend curves of one or more pitch systems; and Based on the analysis, one or more fault indicators are determined for the at least one electrical state and the at least one mechanical state of the pitch system.

[0022] Technical Solution 9. The method according to Technical Solution 7, wherein the one or more fault indicators include at least one of an axis imbalance fault indicator or an axis AVG fault indicator.

[0023] Technical Solution 10. The method according to Technical Solution 1, wherein if the bearing condition indicates that the pitch bearing is damaged, the method further includes identifying the axis of the pitch bearing.

[0024] Technical Solution 11. The method according to Technical Solution 10 further includes scheduling maintenance on the damaged pitch bearing at a later time prior to the failure of the pitch bearing.

[0025] Technical Solution 12. A wind turbine, comprising: Tower; The nacelle is installed on top of the tower; The rotor includes a rotor and a rotatable hub mounted thereto, the rotatable hub including at least one rotor blade mounted thereto via a pitch system, the pitch system including a pitch bearing communicatively coupled to a pitch controller, the pitch controller including a monitoring system for monitoring the pitch bearing, the monitoring system including: At least one first sensor for monitoring at least one electrical state of the pitch system; At least one second sensor for monitoring at least one mechanical state of the pitch system; and, A controller communicatively connected to the at least one first sensor and the second sensor, the controller being configured to perform one or more operations, the one or more operations including: Receive sensor signals from the at least one first sensor and the second sensor; and The bearing condition of the pitch bearing is determined based on at least one electrical state and at least one mechanical state of the pitch system.

[0026] Technical Solution 13. The wind turbine according to Technical Solution 12, wherein the at least one electrical state includes pitch motor current, pitch motor voltage, torque, expected pitch angle from a pitch analyzer model, or at least one of one or more pitch control signals, and the at least one mechanical state includes at least one of pitch angle, pitch speed, or pitch rotor spin speed.

[0027] Technical Solution 14. The wind turbine according to Technical Solution 12, wherein determining the bearing state of the pitch bearing based on the at least one electrical state and the at least one mechanical state of the pitch system further includes: The quantitative relationship between at least one electrical state and at least one mechanical state of the pitch system is derived from the physical three-axis pitch controller model.

[0028] Technical Solution 15. The wind turbine according to Technical Solution 12, wherein determining the bearing state of the pitch bearing based on the at least one electrical state and the at least one mechanical state of the pitch system further includes: One or more fault indicators are used to determine the at least one electrical condition and the at least one mechanical condition of the pitch bearing.

[0029] Technical Solution 16. The wind turbine according to Technical Solution 15, wherein the one or more fault indicators for determining the at least one electrical state and the at least one mechanical state of the pitch system further include: Analyze the defect characteristic trend curves of one or more pitch systems; and Based on the analysis, one or more fault indicators are determined for the at least one electrical state and the at least one mechanical state of the pitch system.

[0030] Technical Solution 17. The wind turbine according to Technical Solution 15, wherein the one or more fault indicators include at least one of an axis imbalance fault indicator or an axis AVG fault indicator.

[0031] Technical Solution 18. The wind turbine according to Technical Solution 12 further includes a later-term maintenance of the damaged pitch bearing prior to the failure of the pitch bearing.

[0032] Technical Solution 19. The wind turbine according to Technical Solution 12, wherein the first sensor and the second sensor include at least one of a proximity sensor, an inductive sensor, a miniature inertial measurement unit (MIMU), a pressure or load sensor, an accelerometer, an acoustic detection and ranging (SODAR) sensor, a light detection and ranging (LIDAR) sensor, or an optical sensor.

[0033] Technical Solution 20. A monitoring system for a bearing system of a wind turbine, the monitoring system comprising: At least one first sensor for monitoring at least one electrical state of the bearing system; At least one second sensor for monitoring at least one mechanical condition of the bearing system; and A controller communicatively connected to the at least one first sensor and the second sensor, the controller being configured to receive sensor signals from the at least one first sensor and the second sensor, and to determine the bearing state of the bearing system based on the at least one electrical state and the at least one mechanical state of the pitch system. Attached Figure Description

[0034] The full and sufficient disclosure of the invention, including its best mode, for those skilled in the art, is set forth in the description with reference to the accompanying drawings, in which: Figure 1 A perspective view of one embodiment of a wind turbine according to the present disclosure is shown; Figure 2 It shows Figure 1 A perspective interior view of one embodiment of the nacelle of the wind turbine shown; Figure 3 It shows Figure 1 A perspective view of one embodiment of a rotor blade of a wind turbine shown in the image; Figure 4 A block diagram of one embodiment of a three-axis pitch system according to the present disclosure is shown; Figure 5 A graph is shown representing an embodiment of the pitch angle (y-axis) versus time (x-axis) for the DC offset of the three rotor blades, 1P pitch, and 2P pitch during independent pitch control operations according to this disclosure. Figure 6 A perspective view of one embodiment of a pitch bearing for a wind turbine according to the present disclosure is shown; Figure 7 A partial cross-sectional view of one embodiment of a pitch bearing for a wind turbine according to the present disclosure is shown; Figure 8 A schematic diagram of one embodiment of a pitch system with a monitoring system according to the present disclosure is shown; Figure 9 A schematic diagram of one embodiment of a controller for a bearing assembly according to the present disclosure is shown; Figure 10 A flowchart illustrating an embodiment of a method for monitoring a pitch system of a wind turbine according to this disclosure is shown; and Figure 11 An embodiment of a characteristic trend curve for pitch bearing defects according to this disclosure is shown.

[0035] Figure Labels 10 Wind turbines 12 towers 16 Cabin 18 rotors 20 Rotatable hubs 22 Rotor blades 23. Leaf base 24. Leaf tips 25 Generators 26 Rotor shaft 27 Ontology 28 Generator Shaft 29 Pressure side 30 Gearbox 31 Suction side 32 controllers 33. Prelude 34 Control Cabinet 35. Trailing edge 36 plates 37 Wingspan 38 Pitch drive mechanism 39 wing chords 40 Pitch Axis 41 Root attachment assembly 42 Pitch Bearing 43 barrel nut 44 Yaw drive mechanism 45 Root bolts 46 Yaw bearing 47. Root end 48 Spherical plug 50 bearing assembly 51 Spherical plug body 52 Outer ring 54 Inner Circle 56 Roller Elements 58 pitch drive motors 60 Pitch Drive Gearbox 62 Pitch drive pinion 64 gear teeth 66 First Rolling Track 68 First Rolling Track 70 Pitch System 72 Monitoring System 74 controllers 76 (one or more) first sensors 78 (one or more) second sensors 82 (one or more) processors 84 (one or more) memory devices 86 Communication Module 88 Sensor Interface 100 methods 102 Methods and Steps 104 Methods and Steps 106 Methods and Steps 108 Methods and Steps. Detailed Implementation

[0036] Reference will now be made in detail to embodiments of the invention, one or more of which are illustrated in the accompanying drawings. These various examples are provided by way of illustrative purposes and are not intended to limit the invention. Indeed, those skilled in the art will appreciate that various modifications and variations can be made to the invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in conjunction with another embodiment to produce yet another embodiment.

[0037] Generally, this disclosure relates to a system and method for monitoring the health of pitch bearings, which uses pitch system characterization with both electrical characteristics (e.g., pitch motor current, voltage, torque, expected pitch angle from a pitch analyzer model, or one or more pitch control signals) and mechanical characteristics (e.g., blade pitch angle, blade pitch speed, and pitch rotor spin speed) to improve the early detectability of pitch bearing degradation. The quantitative relationship between the mechanical and electrical characteristics is derived from a physical three-axis pitch system controller model. Furthermore, this disclosure uses two sets of fault indicators (FIs) for selecting mechanical and electrical characteristics (i.e., a fusion of axis imbalance FI and axis AVG FI) to improve the probability of fault detection. These fault indicators are proposed based on trend curves of analyzed pitch system defect characteristics. This disclosure can also be used to identify which axis of the detected turbine is faulty. This solution gives operators the opportunity to plan maintenance procedures before unnecessary turbine downtime and economic losses are unavoidable. By implementing combined fault indicator (FI) analysis, the fault detection rate can be significantly improved compared to purely electrical marker analysis.

[0038] In one embodiment, the invention compares operating data from all rotor blade axes. In another embodiment, the invention performs the analysis on a single axis. PFA and PAA can also be applied to each axis for fault detection. In this case, the trend of the average PFA and / or PAA for each axis can serve as a direct indicator of the severity of the pitch bearing fault.

[0039] This invention is described herein as relating to wind turbine bearings, including at least yaw bearings, pitch bearings, and / or similar types. However, it should be understood that the systems and methods according to the principles of the invention are not limited to use with wind turbines, but are applicable to any suitable bearing application. For example, it should be understood that the systems and methods described herein are configured to fit within conventional slewing bearings and / or modified slewing bearings known in the art and developed thereafter, and are not limited to a particular slewing bearing construction.

[0040] Now refer to the attached diagram. Figure 1A side view of one embodiment of a wind turbine 10 is shown. As shown, the wind turbine 10 generally includes a tower 12 extending from a support surface 14 (e.g., the ground, a concrete pad, or any other suitable support surface). Therefore, it should be understood that the wind turbine 10 described herein can be an onshore or offshore wind turbine. Furthermore, the wind turbine 10 may also include a nacelle 16 mounted on the tower 12 and a rotor 18 coupled to the nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending outward from the hub 20. For example, in the illustrated embodiment, the rotor 18 includes three rotor blades 22. However, in alternative embodiments, the rotor 19 may include more or fewer than three rotor blades 22. Each rotor blade 22 may be spaced apart around the hub 20 to allow rotation of the rotor 19 to allow kinetic energy from the wind to be converted into usable mechanical energy, and subsequently into electrical energy. For example, the hub 20 is rotatably coupled to a generator 25 positioned within the nacelle 16. Figure 2 On top of that, so that electrical energy can be generated.

[0041] Now see Figure 2 , showed Figure 1 The diagram shows a simplified internal view of one embodiment of the nacelle 16 of the wind turbine 10. As shown, a generator 25 may be housed within the nacelle 16 and supported on top of a platform 36. Generally, the generator 25 may be coupled to a rotor 18 to generate electricity from the rotational energy produced by the rotor 18. For example, as shown in the illustrated embodiment, the rotor 18 may include a rotor shaft 26 coupled to a hub 20 for rotation therewith. The rotor shaft 26 may then be rotatably coupled to a generator shaft 28 of the generator 25 via a gearbox 30. As generally understood, the rotor shaft 26 may provide a low-speed, high-torque input to the gearbox 30 in response to rotation of the rotor blades 22 and the hub 20. The gearbox 30 may then be configured to convert the low-speed, high-torque input into a high-speed, low-torque output to drive the generator shaft 28, and thus the generator 25.

[0042] The wind turbine 10 may also include a turbine controller 32 centrally located within the nacelle 16. Furthermore, as shown, the turbine controller 32 is housed within a control cabinet 34. Additionally, the turbine controller 32 can be communicatively coupled to any number of components of the wind turbine 10 to control the operation of these components and / or implement various corrections as described herein.

[0043] See Figure 2 and 4A typical pitch system 70 has a three-axis unit driven by a pitch drive mechanism 38 configured to rotate each rotor blade 22 about its corresponding pitch axis 40 via a pitch bearing 42, thereby allowing adjustment of the orientation of each rotor blade 22 relative to the wind direction. Each pitch drive mechanism 38 includes a pitch drive motor 58 regulated by a controller 74 within it, so that the rotor blade 22 can pitch independently under normal operation. It should be understood that the pitch drive motor 58 can be a direct current (DC) motor or an alternating current (AC) motor. Therefore, when the power generated by the corresponding wind exceeds a threshold, independent pitch control is applied to reduce the tension on the rotor blade 22 and the tower 12 during operation. For wind turbines operating under independent pitch control, such as... Figure 5 As shown, during independent pitch control operations, each axis 40 is commanded to be at different pitch angles at different rotor positions, including 1P pitch, 2P pitch, and DC offset commands, as well as several other common offset items. A 1P pitch command instructs rotor blade 22 to pitch once per rotation, while a 2P pitch command instructs rotor blade 22 to pitch twice per rotation. The command values ​​are updated online based on real-time measurements from a proximity probe mounted on the wind turbine 10. In some embodiments, although each rotor blade 22 pitches independently with different load commands, its AC command components (e.g., 1P and 2P commands) remain balanced, having the same AC magnitude but shifted by 120 degrees.

[0044] Similarly, the wind turbine 10 may include one or more yaw drive mechanisms 44 communicatively coupled to the turbine controller 32, wherein each yaw drive mechanism 44 is configured to change the angle of the nacelle 16 with respect to the wind (e.g., by engaging the yaw bearing 46 of the wind turbine 10).

[0045] Now see Figure 3 This illustrates aspects of the subject matter. Figure 1 and 2A perspective view of one of the rotor blades 22 shown. As shown, the rotor blade 22 includes a blade root 23 configured for mounting the rotor blade 22 to the hub 20, and a blade root 23 disposed opposite to the blade root 23. The body 27 of the rotor blade 22 may extend longitudinally between the blade root 23 and the blade tip 24, and may generally serve as the outer shell of the rotor blade 22. As generally known, the body 27 may define an aerodynamic profile (e.g., by defining an airfoil cross section, such as a symmetrical or arcuate airfoil cross section) to allow the rotor blade 22 to harvest kinetic energy from the wind using known aerodynamic principles. Thus, the body 27 may generally include a pressure side 29 and a suction side 31 extending between the leading edge 33 and the trailing edge 35. Furthermore, the rotor blade 22 may have a span 37 defining the total length of the body 27 between the blade root 23 and the blade tip 24, and a chord 39 defining the total length of the body 27 between the leading edge 33 and the trailing edge 35. As generally understood, when the body 27 extends from the blade root 23 to the blade tip 24, the chord 39 can change its length relative to the wingspan 37.

[0046] Furthermore, as shown, the rotor blade 22 also includes a plurality of T-bolts or root attachment assemblies 41 for attaching the blade root 23 to the hub 20 of the wind turbine 10. Generally, each root attachment assembly 41 may include a cylindrical nut 43 mounted within a portion of the blade root 23, and a root bolt 45 attached to and extending from the cylindrical nut 43 to project outward from the root end 47 of the blade root 23. By projecting outward from the root end 47, the root bolt 45 can be generally used to attach the blade root 23 to the hub 20 (e.g., via one of the pitch bearings 42).

[0047] A healthy wind turbine has a balanced three-axis pitch system 70. Furthermore, the excitation required to pitch each rotor blade at a 22-degree angle is approximately the same. For a wind turbine with a pitch bearing failure, the pitch motor for the damaged blade axis requires additional excitation to adjust its own blades at the commanded position, compared to the other healthy axes. Based on these assumptions, this disclosure relates to a pitch bearing fault diagnosis system with a combined system-level fault indicator. The combined system-level fault indicator consists of at least two fault indicators (FIs), as discussed below.

[0048] also, Figure 6-8An embodiment of a bearing assembly 50 according to this disclosure is shown. More specifically, as shown, the bearing assembly 50 includes a pitch bearing 42. It should be understood that this disclosure is described with reference to a pitch bearing, but other bearings are applicable within the spirit and scope of the invention, such as, for example, yaw bearings. As shown, the pitch bearing 42 has an outer ring 52, an inner ring 54, and a plurality of rolling elements 56 disposed between the outer ring 52 and the inner ring 54. As generally known, the outer ring 52 may be generally configured to be mounted to the hub flange of the hub 20 using a plurality of hub bolts and / or other suitable fastening mechanisms. Similarly, the inner ring 54 may be configured to be mounted to the blade root 23 using root bolts 45 of a root attachment assembly 41.

[0049] Furthermore, the roller element 56 as described herein may include any or a combination of one or more balls, rollers, tapered rollers, cylindrical rollers, columnar elements, or any other suitable roller element. Furthermore, any suitable number of roller elements 56 may be used. Furthermore, the roller elements 56 may be arranged in any suitable configuration. For example, as... Figure 6 As shown, two rows of roller elements 56 are used, with each roller element 56 circumferentially spaced between the outer ring 52 and the inner ring 54. In other embodiments, a single row or multiple rows of axially spaced roller elements 56 may be used in the bearing assembly 50 to provide additional strength. For example, in various embodiments, three or more rows of roller elements 56 may be used.

[0050] See details Figure 7 and 8 The roller elements 56 are configured to be received within separate raceways defined between the inner ring 54 and the outer ring 52. Specifically, a first raceway 66 is defined between the inner ring 54 and the outer ring 52 for receiving a first row of roller elements 56, and a second raceway 68 is defined between the inner ring 54 and the outer ring 52 for receiving a second row of roller elements 56. Thus, as... Figure 6 , 7 As shown in Figure 8, the outer ring 52 of the pitch bearing 42 may further include at least one ball plug 48 to allow the roller element 56 to be positioned between the outer ring 52 and the inner ring 54 and to enter the first raceway 66 and the second raceway 68. For example, as shown in Figure 8. Figure 6 and 8As shown, the outer ring 52 includes two ball plugs 48 (i.e., one per row of roller elements 56). Therefore, the ball plugs 48 are removable, and the roller elements 56 can be inserted via the outer ring 52 into one of the first raceways 66 and the second raceway 68. In this embodiment, each of the first raceways 66 and the second raceway 68 may be defined by separate walls of the outer ring 52 and the inner ring 54. For example, as shown, the first raceway 66 is defined by a first outer raceway wall of the outer ring 52 and a first inner raceway wall of the inner ring 54. Similarly, the second raceway 68 is defined by a second outer raceway wall of the outer ring 52 and a second inner raceway wall of the inner ring 54.

[0051] Therefore, the inner ring 54 can be configured to rotate relative to the outer ring 52 (via the roller element 56) to allow adjustment of the pitch angle of each rotor blade 22. As described, the relative rotation of the outer ring 52 and the inner ring 54 can be achieved using a pitch drive mechanism 38 mounted within a portion of the hub 20. Generally, the pitch drive mechanism 38 can include any suitable components and can have any suitable configuration that allows the pitch drive mechanism 38 to function as described herein. For example, as Figure 2 As shown, the pitch drive mechanism 38 may include a pitch drive motor 58 (e.g., an electric motor), a pitch drive gearbox 60, and a pitch drive pinion 62. In this embodiment, the pitch drive motor 58 may be coupled to the pitch drive gearbox 60 so that the pitch drive motor 58 provides mechanical force to the gearbox 60. Similarly, the gearbox 60 may be coupled to the pitch drive pinion 62 to rotate with it. The pitch drive pinion 62 may then be rotatably engaged with the inner ring 54. For example, as... Figure 6 As shown, a plurality of gear teeth 64 may be formed along the inner circumference of the inner ring 54, wherein the gear teeth 64 are configured to mesh with corresponding gear teeth formed on the pitch drive pinion 62. Therefore, due to the meshing of the gear teeth 64, the rotation of the pitch drive pinion 62 causes the inner ring 54 to rotate relative to the outer ring 52, and thus the rotor blades 22 to rotate relative to the hub 20.

[0052] Now see Figure 8 and 9The figure illustrates various components of a pitch system 70 including a monitoring system 72 according to the present disclosure. More specifically, as shown, the pitch system 70 includes a pitch bearing 42, a pitch drive mechanism 38, a first sensor 76 and a second sensor 78, and a controller 74 communicatively coupled to the first sensor 76 and the second sensor 78. More specifically, the first sensor 76 may be configured to monitor or measure one or more electrical states of the pitch system 70, including but not limited to pitch motor current, pitch motor voltage, torque, one or more pitch control signals, or any other electrical state. In another embodiment, the second sensor 78 may be configured to monitor or measure mechanical states, which may include pitch angle, pitch speed, pitch rotor spin speed, or any other mechanical state of the pitch system 70. Therefore, the controller 74 is configured to receive sensor signals from the first sensor 76 and the second sensor 78 and determine the bearing state of the pitch bearing 42 based on the electrical and mechanical states of the pitch system 70.

[0053] In addition, such as Figure 9 As shown, the controller 74 may include one or more processors 82 and associated memory devices 84, configured to perform various computer-implementable functions (e.g., performing methods, steps, calculations, etc., and storing related data as disclosed herein). Furthermore, the controller 74 may also include a communication module 86 to facilitate communication between the controller 74 and the first sensor 76 and the second sensor 78. Additionally, the communication module 86 may include a sensor interface 88 (e.g., one or more analog-to-digital converters) to allow signals transmitted from the first sensor 76 and the second sensor 78 to be converted into signals that can be understood and processed by the processor 82. It should be appreciated that the first sensor 76 and the second sensor 78 can be communicatively coupled to the communication module 86 using any suitable means. For example, as... Figure 9 As shown, the first sensor 76 and the second sensor 78 can be connected to the sensor interface 88 via a wired connection. However, in other embodiments, the first sensor 76 and the second sensor 78 can be connected to the sensor interface 88 via a wireless connection, such as by using any suitable wireless communication protocol known in the art. Therefore, the processor 82 can be configured to receive one or more signals from the first sensor 76 and the second sensor 78. Furthermore, the controller 74 and the first sensor 76 and the second sensor 78 can also be integrated into a single package, wherein one or more integrated packages can be used in the bearing assembly 50.

[0054] As used herein, the term "processor" refers not only to integrated circuits included in a computer as understood in the art, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and other programmable circuits. Processor 82 may also be configured to compute advanced control algorithms and communicate with a variety of Ethernet-based or serial protocols (Modbus, OPC, CAN, etc.) and classical analog or digital signals. Furthermore, memory device 84 may generally include memory elements, including but not limited to computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, optical disc read-only memory (CD-ROM), magneto-optical discs (MOD), digital versatile discs (DVDs), and / or other suitable memory elements. This memory device 84 may be generally configured to store suitable computer-readable instructions that, when implemented by processor 82, configure controller 74 to perform the various functions described herein.

[0055] In another embodiment, the first sensor 76 and the second sensor 78 described herein may include any one or a combination of the following sensors: proximity sensor, inductive sensor, miniature inertial measurement unit (MIMU), pressure or load sensor, accelerometer, acoustic detection and ranging (SODAR) sensor, light detection and ranging (LIDAR) sensor, optical sensor, or the like.

[0056] Now see Figure 10 The diagram shows a pitch system for monitoring the wind turbine 10 (e.g., as shown in the image). Figure 7A flowchart of one embodiment of method 100 for the pitch system 70 is shown below. As shown at 102, method 100 includes measuring at least one electrical state of the pitch system 70 via one or more first sensors 76. As shown at 104, method 100 includes measuring at least one mechanical state of the pitch system 70 via one or more second sensors 76. As shown at 106, method 100 includes receiving sensor signals representing the electrical and mechanical states of the pitch system 70 via a controller 74. As shown at 108, method 100 includes determining the bearing state of the pitch bearing 42 based on the electrical and mechanical states of the pitch system 70 via the controller 74. For example, in one embodiment, the controller 74 may determine the bearing state of the pitch bearing 42 by obtaining a quantitative relationship between the electrical and mechanical states of the pitch system 70. More particularly, in this embodiment, the controller 74 may derive the quantitative relationship between the electrical and mechanical states from a physical three-axis pitch controller model. In other embodiments, method 100 may further include monitoring at least one wind condition (e.g., wind speed) of the wind turbine 10. In this embodiment, method 100 may include determining the bearing condition of the pitch bearing 42 based on electrical condition, mechanical condition, and wind speed.

[0057] In an additional embodiment, the controller 74 may determine one or more fault indicators (FIs) for the electrical and mechanical states of the pitch system 70. These fault indicators may then be trended over time. For example, as... Figure 11 The diagram illustrates a graph of one embodiment of a pitch bearing defect fault indicator trend curve, specifically showing the increasing severity of the fault over time. Therefore, in some embodiments, the controller 74 can analyze the pitch system defect characteristic trend curve, which can be used to describe the life cycle of the pitch bearing 42. Thus, in this embodiment, the controller 74 can determine fault indicators for the electrical and mechanical states of the pitch system 70 based on the analysis. More specifically, in one embodiment, the fault indicators may include an axis imbalance fault indicator or an axis AVG fault indicator. The axis imbalance fault indicator provides a representation of the imbalance characteristics of the pitch system 70 or an index of the severity of the system's imbalance / asymmetry characteristics, while the axis AVG fault indicator represents the average excitation level for the three-axis pitch system 70.

[0058] Furthermore, as shown in the figure, if the pitch bearing 42 is in a healthy condition (e.g., Figure 11 In the "adolescent" stage of the pitch system, the pitch drive motor 58 will operate in a roughly balanced manner but with a 120-degree shift. Therefore, the "axis imbalance FI" of the pitch system 70 formed by the three axes is negligible, and the "axis AVG FI" remains at a reasonably small value. Alternatively, if a defect in the pitch bearing 42 begins to occur on one axis (e.g., ...), Figure 11 In the "1-axis defect" stage, the excitation of the motor driving the defective bearing will increase; therefore, the asymmetric "axis imbalance FI" between the pitch motors will increase significantly. In addition, the average excitation "axis AVG FI" for the three-axis system also increases. If two or three pitch bearings 42 begin to fail (e.g., Figure 11 In the stages of ">1 axis defect", "3 axis defect", and "3 axis defect (1 range)", the asymmetric characteristic of the pitch system 70, "axis imbalance FI", can be alleviated compared to the previous stages; however, "axis AVG FI" will increase rapidly.

[0059] If the "Axis Imbalance" and "Axis AVG" FI values ​​are low, the pitch system 70 is relatively healthy. If at least one FI value is high, the wind turbine can be flagged as damaged. The higher the "Axis Imbalance FI" or "Axis AVG FI" value, the higher the probability of a damaged pitch bearing. In practice, an alarm can be triggered if at least one FI deviates from a predetermined threshold or an online calculated amount from the baseline or healthy wind pitch system.

[0060] Based on the above description of how to use combined FI to detect pitch bearing failures, various software solutions can be used for validation, namely, Pitch Symmetric Component Analysis (PSA), Pitch Basic AC Analysis (PFA), and / or Pitch Angle Based Analysis (PAA). In each solution, "Axis Imbalance FI" and "Axis AVG FI" are quantified by the relevant mechanical and / or electrical characteristics, respectively. PSA means that the sequential components used for the pitch system 70 are used as a combined failure severity index. More precisely, the system negative-sequence component of the pitch-speed normalized motor armature current is used as "Axis Imbalance FI," and an equal amount of the positive-sequence component is used as "Axis AVG FI." In PFA, "Axis Imbalance FI" is calculated from the standard deviation of the pitch-speed normalized baseline AC component of each pitch motor current to represent the asymmetric / unbalanced state of the pitch system, while "Axis AVG FI" is calculated from the three-axis average of the same normalized pitch current ripple amount. PAA requires a pitch analyzer model in the turbine controller to provide the expected pitch angle quantity and direct pitch angle measurement. The difference between the measured angle and the expected angle for each blade is used as a mechanical characteristic. Similar to PFA, the standard deviation of the three axes and the average value of "pitch angle variation" are used as "axis imbalance FI" and "axis AVG FI", respectively.

[0061] For PSA, pitch bearing defect detection is based on symmetric component analysis. Symmetric component analysis is generally used for the analysis of multiphase AC systems. Since the pitch motor is a single-phase DC motor, symmetric component analysis cannot be directly applied to each motor. However, during independent pitch control operations, AC ripple is intentionally introduced for each DC pitch motor via given 1P and 2P pitch commands; simulation analysis of the pitch system and field data shows that the AC oscillations of the three individual pitch motors (one for each rotor blade 22) together form a system that can be considered a three-phase system. Therefore, symmetric component analysis can be applied to the three axes of the pitch system to indicate the deterioration of pitch bearing defects.

[0062] Symmetric component analysis can be applied to motor current and pitch speed, or torque and pitch speed. Typically, no direct torque measurement is available. Motor current measurement is generally easier and more accurate. Therefore, in one embodiment, the proposed method can be applied to both motor current and blade pitch speed. Furthermore, if torque measurement is available, it can be used instead of motor current. Motor current can be measured directly using an additional data acquisition system or by using a pitch motor converter.

[0063] To perform symmetric component analysis, the complex pitch current vector and complex pitch velocity vector are calculated as follows: in ; , and It is the time-domain armature current of the three pitch motors; and , and It is the time-domain blade pitch speed used for three blades.

[0064] The calculated complex pitch current and pitch speed vectors are transformed from the time domain to the frequency domain, for example, by applying Fast Fourier Transform (FFT) or spectral density estimation or real-time algorithms.

[0065] Complex pitch current The AC positive sequence component can be identified as the pitch spin velocity (rotor velocity of the pitch system) in the spectrum. The nearest maximum discrete Fourier transform (DFT) bin. The pitch current vector can also be found. The negative sequence component is used as the negative value of the AC fundamental frequency component. The nearest maximum DFT box. The positive and negative sequence components of the pitch speed can be determined in a similar manner. and .

[0066] For a pitch system well-tuned by independent pitch control, the three pitch blade angles operate in a substantially balanced manner (i.e., the same AC pitch size, but a 120-degree phase shift), regardless of system defects; therefore The symmetric component model for a multi-axis pitch system can be simplified to the equation shown in equation (3).

[0067] in, Similar to the concept of positive (negative) sequence impedance in unbalanced circuit sequence networks, and representing the amount of positive (negative) sequence current; These are the positive-sequence and negative-sequence motor current components; These are the positive and negative sequence pitch speed components; and Similar to the transfer impedance used for the same RLC circuit sequence network.

[0068] Ideally, if the pitch system 70 and all measurement channels are preferably symmetrical, the transmission impedance will be zero. The transmission impedance is by no means exactly zero and is related to the inherent imbalance of the measurement channels, the inherent asymmetry of the pitch system 70, and random wind conditions. If the pitch system 70 has at least one damaged pitch bearing, the transmission impedance increases significantly and can be used as a direct indicator of the system's imbalance level.

[0069] When independent pitch control is applied, it can be observed from the simplified model in equation (3) that... and ,Depend on The magnitudes of the positive and negative sequence components of the standardized pitch motor armature current vector can be directly used as a set of combined fault indicators (FIs) to indicate the “unbalance” and “AVG increase” characteristics of a multi-axis pitch system, as shown in equations (4) and (5).

[0070] Negative order FI: Ascending order FI: PFA can also be applied to motor current and pitch speed or torque and pitch speed. Furthermore, PFA is based on spectral analysis for independent axes under steady-state conditions, replacing the entire three-axis system in PSA. Under independent pitch control steady-state conditions, noticeable AC oscillations exist in the motor armature current, and corresponding pitch speed and angular waveforms. The main AC ripples are those directly related to the 1P and 2P pitch commands. For simplicity, the examples shown will focus only on the fundamental velocity components and the first axis. For the first axis, the magnitude of the fundamental AC current ripple is determined by observing the rotor spin speed. The nearest largest DFT bin is determined and represented as The basic velocity ripple is determined in a similar manner as follows: Under steady state, the magnitudes of current and velocity ripples... and Keep.

[0071] and The magnitude of the transfer function between them (velocity-normalized basic current ripple) This represents the current excitation required to make the blade pitch one unit. Similarly, the basic current ripple, normalized to the speed of rotor blades 2 and 3, is calculated and... and Indicated. Given the above quantities, "Axis AVG FI" or the balancing excitation for multi-axis systems is obtained by taking , and The average value is used for calculation; and "axis imbalance FI", i.e., the asymmetry index of the pitch system, is calculated by... , and The standard deviation represents.

[0072] Note that, similar to PSA, the standard deviation and the average value of the basic pitch motor current ripple alone are insufficient to accurately represent the severity of both systems. This is because the magnitude of the command blade pitch speed, determined by the load command, varies from turbine to turbine. A high average value (standard deviation) for current ripple can be introduced solely by a high 1P pitch command, not by pitch bearing failure. Therefore, both pitch motor current and pitch speed need to be included to obtain both "axis imbalance FI" and "axis AVG FI".

[0073] The PAA method differs from the PSA and PFA solutions presented in the previous section in that it only requires mechanical pitch angle characteristics and does not require direct measurement of motor current or torque. Furthermore, this method requires a pitch analyzer model to obtain the expected pitch position for each rotor blade, rather than just a direct measurement of the blade angle.

[0074] If raw data is obtained under steady-state conditions, the angular difference (in degrees) between the expected measurement and the direct measurement at each blade position is calculated at each sampling point as follows: and For well-tuned systems, pitch angle differences are negligible. However, if a blade has a bearing defect, the expected blade angle will be less accurate than in a healthy turbine because the pitch analyzer model knows very little about the real-time pitch bearing condition, and the difference between the expected location and the actual measurement at each sampling point will increase significantly. To quantify the increase in pitch angle differences, the root mean square (RMS) of the pitch angle difference is calculated and expressed as... and .

[0075] "Axis AVG FI" or average excitation for multi-axis systems is obtained by taking the angle difference RMS data. and The average mean was obtained; "axis imbalance FI", i.e., the asymmetry index of the pitch system, was obtained from the same set of RMS data. and The standard deviation is expressed as follows. In fact, not only RMS has been calculated, but also the DC, fundamental AC, and second harmonic AC components of the pitch angle difference have been calculated for field data verification.

[0076] In some embodiments, the derived FI quantity may also be averaged over a given period of time (e.g., several weeks) or a selected number of files (e.g., 20 files) to obtain a more robust and reliable sorting queue or decision regarding the condition of the pitch bearing.

[0077] The proposed pitch bearing fault detection solutions are all based on physical models, requiring knowledge of general steady-state DC pitch motor models and general multiphase AC system sequence models; however, they do not require model parameters. It will not only indicate which wind turbine has a pitch bearing fault, but also which of the three axes used for that turbine is defective. From a computational complexity perspective, PAA only focuses on time-domain RMS calculations, thus having the lowest computational requirements; PSA only requires symmetric component analysis and frequency decomposition of system quantities, thus having slightly higher computational complexity; PFA requires spectral analysis of each axis variable, meaning it has the highest computational complexity among the three. On the other hand, PAA requires knowledge of the pitch analyzer model, which may not be applicable to all wind turbines. If not, only PSA and PFA can be used to diagnose pitch bearing faults.

[0078] In several embodiments, if the determined bearing condition indicates that the pitch bearing 42 is damaged, method 100 may further include identifying the axis of the damaged pitch bearing 42. Therefore, the operator can plan to repair the damaged pitch bearing before the wind turbine fails, avoiding unnecessary downtime and energy loss. For example, in one embodiment, method 100 may include scheduling maintenance on the damaged pitch bearing 42 at a later time, but before the pitch bearing 42 fails. Thus, in specific embodiments, by combining electrical and mechanical aspects, this disclosure provides improved detection accuracy, trend, and severity assessment of the pitch system 70 and associated rotor blades 22.

[0079] This written description uses examples to disclose the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including making and using any apparatus or system, and performing any incorporated methods. The scope of the invention may include other examples that will occur to those skilled in the art. Such other embodiments are expected to be within the scope of the invention if they include structural elements that are not different from the written language of the invention, or if they include equivalent structural elements that are not substantially different from the written language of the invention.

Claims

1. A method for monitoring a pitch system of a wind turbine, the pitch system having at least a pitch bearing, the method comprising: At least one electrical state of the pitch system is monitored via one or more first sensors; At least one mechanical state of the pitch system is monitored via one or more second sensors; as well as A controller, communicatively connected to the one or more first and second sensors, receives sensor signals representing at least one electrical state and at least one mechanical state of the pitch system; as well as The controller determines the bearing condition of the pitch bearing based on at least one electrical state and at least one mechanical state of the pitch system; The determination of the bearing condition of the pitch bearing based on the at least one electrical condition and the at least one mechanical condition of the pitch system further includes determining one or more fault indicators for the at least one electrical condition and the at least one mechanical condition of the pitch system. The one or more fault indicators include at least one of an axis imbalance fault indicator or an axis AVG fault indicator.

2. The method according to claim 1, wherein, The at least one electrical state includes pitch motor current, pitch motor voltage, torque, expected pitch angle from the pitch analyzer model, or at least one of one or more pitch control signals.

3. The method according to claim 1, wherein, The at least one mechanical state includes at least one of pitch angle, pitch speed, or pitch rotor spin speed.

4. The method according to claim 1, further comprising monitoring the wind speed of the wind turbine, and determining the bearing condition of the pitch bearing based on the at least one electrical state, the at least one mechanical state of the pitch system, and the wind speed.

5. The method according to claim 1, wherein, Determining the bearing condition of the pitch bearing based on the at least one electrical state and the at least one mechanical state of the pitch system further includes: A quantitative relationship is derived between the at least one electrical state and the at least one mechanical state of the pitch system.

6. The method of claim 5 further includes deriving a quantitative relationship between the at least one electrical state and the at least one mechanical state of the pitch system from a physical three-axis pitch controller model.

7. The method according to claim 1, wherein, The one or more fault indicators for determining the at least one electrical state and the at least one mechanical state of the pitch system further include: Analyze the defect characteristic trend curves of one or more pitch systems; and Based on the analysis, one or more fault indicators are determined for the at least one electrical state and the at least one mechanical state of the pitch system.

8. The method according to claim 1, wherein, If the bearing condition indicates that the pitch bearing is damaged, the method further includes identifying the axis of the pitch bearing.

9. The method of claim 8 further includes scheduling maintenance on the damaged pitch bearing at a later time prior to the failure of the pitch bearing.

10. A wind turbine, comprising: Tower; The nacelle is installed on top of the tower; The rotor includes a rotor and a rotatable hub mounted thereto, the rotatable hub including at least one rotor blade mounted thereto via a pitch system, the pitch system including a pitch bearing communicatively coupled to a pitch controller, the pitch controller including a monitoring system for monitoring the pitch bearing, the monitoring system including: At least one first sensor for monitoring at least one electrical state of the pitch system; At least one second sensor for monitoring at least one mechanical state of the pitch system; and, A controller communicatively connected to the at least one first sensor and the second sensor, the controller being configured to perform one or more operations, the one or more operations including: Receive sensor signals from the at least one first sensor and the second sensor; and The bearing condition of the pitch bearing is determined based on at least one electrical state and at least one mechanical state of the pitch system; The determination of the bearing condition of the pitch bearing based on the at least one electrical condition and the at least one mechanical condition of the pitch system further includes determining one or more fault indicators for the at least one electrical condition and the at least one mechanical condition of the pitch system. The one or more fault indicators include at least one of an axis imbalance fault indicator or an axis AVG fault indicator.

11. The wind turbine according to claim 10, wherein, The at least one electrical state includes pitch motor current, pitch motor voltage, torque, expected pitch angle from the pitch analyzer model, or at least one of one or more pitch control signals, and the at least one mechanical state includes at least one of pitch angle, pitch speed, or pitch rotor spin speed.

12. The wind turbine according to claim 10, wherein, Determining the bearing condition of the pitch bearing based on the at least one electrical state and the at least one mechanical state of the pitch system further includes: The quantitative relationship between at least one electrical state and at least one mechanical state of the pitch system is derived from the physical three-axis pitch controller model.

13. The wind turbine according to claim 10, wherein, The one or more fault indicators for determining the at least one electrical state and the at least one mechanical state of the pitch system further include: Analyze the defect characteristic trend curves of one or more pitch systems; and Based on the analysis, one or more fault indicators are determined for the at least one electrical state and the at least one mechanical state of the pitch system.

14. The wind turbine of claim 10, further comprising scheduling maintenance on the damaged pitch bearing at a later time prior to the failure of the pitch bearing.

15. The wind turbine according to claim 10, wherein, The first sensor and the second sensor include at least one of a proximity sensor, an inductive sensor, a miniature inertial measurement unit (MIMU), a pressure or load sensor, an accelerometer, an acoustic detection and ranging (SODAR) sensor, a light detection and ranging (LIDAR) sensor, or an optical sensor.

16. A monitoring system for a bearing system of a wind turbine, the monitoring system comprising: At least one first sensor for monitoring at least one electrical state of the bearing system; At least one second sensor for monitoring at least one mechanical condition of the bearing system; as well as A controller communicatively connected to the at least one first sensor and the second sensor, the controller being configured to receive sensor signals from the at least one first sensor and the second sensor, and to determine the bearing state of the bearing system based on the at least one electrical state and the at least one mechanical state of the bearing system; The determination of the bearing state of the bearing system based on the at least one electrical state and the at least one mechanical state of the bearing system further includes determining one or more fault indicators for the at least one electrical state and the at least one mechanical state of the bearing system. The one or more fault indicators include at least one of an axis imbalance fault indicator or an axis AVG fault indicator.

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