System and method for detecting deterioration in a wind turbine generator bearing

Abstract

A method for preventing damage in a bearing of a generator includes monitoring, via a controller, one or more electrical signals of a power conversion assembly. The method also includes converting the electrical signal(s) to a frequency domain. Further, the method includes extracting one or more spectral components in a frequency band of the frequency domain around one or more known characteristic frequencies of the bearing. Moreover, the method includes determining at least one characteristic of the spectral component(s) in the frequency band. Further, the method includes comparing the characteristic(s) of the spectral component(s) in the frequency band to at least one baseline value. The method also includes generating a fault signal or a baseline signal for the bearing based on the comparison. In response to the fault signal being generated, the method includes implementing a control action.

Description

Technical Field

[0001] This disclosure generally relates to wind turbines, and more particularly to systems and methods for detecting deterioration (such as electrical discharge machining or lubricant deterioration) in bearings of generators using electrical characterization analysis. Background Technology

[0002] Wind power is considered one of the cleanest and most environmentally friendly energy sources available today, and wind turbines are receiving increasing attention in this area. A modern wind turbine typically consists of a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture the kinetic energy of the wind using the known airfoil principle. For example, rotor blades typically have an airfoil cross-sectional profile, such that during operation, air flowing over the blades creates a pressure difference between the sides. Therefore, lift, directed from the pressure side towards the suction side, acts on the blades. This lift generates torque on the main rotor shaft, which is then geared to the generator to produce electricity.

[0003] In many wind turbines, the generator can be electrically connected to a bidirectional power converter, which includes a rotor-side converter connected to a line-side converter via a regulated DC link. Such a wind turbine power system is commonly referred to as a doubly-fed induction generator (DFIG). DFIG operation is typically characterized by the rotor circuit receiving current from the current-regulated power converter. Accordingly, the wind turbine generates variable mechanical torque due to variable wind speeds, and the power converter ensures that this torque is converted into electrical output at the same frequency as the grid.

[0004] During operation, wind impacts the rotor blades, converting wind energy into mechanical rotational torque that drives the low-speed shaft. The low-speed shaft is configured to drive a gearbox, which then increases the low rotational speed of the low-speed shaft to drive the high-speed shaft at an increased rotational speed. The high-speed shaft is substantially coupled to the generator to rotatably drive the generator rotor. In this way, a rotating magnetic field can be induced by the generator rotor, and a voltage can be induced within the generator stator. Rotational energy is converted into electrical energy by the electromagnetic field connecting the rotor and stator, and this electrical energy is supplied to the power grid via a grid circuit breaker. Therefore, the main transformer increases the voltage amplitude of the electrical power, allowing the converted electrical power to be further transmitted to the power grid.

[0005] While capacitive coupling between the rotor and stator is not a major factor in the generated power, it can introduce undesirable rotor shaft voltages in the rotor. Under normal operating conditions, the current driven by rotor shaft voltages is safely dissipated through grounding brushes that contact the rotor and ground. Additionally, insulation is provided between the bearing housing and the frame. However, if the grounding path through the grounding brushes deteriorates and the bearing insulation fails, the high common-mode voltage injected through the rotor-side inverter can potentially damage the bearings via electrical discharge machining (EDM). EDM causes pitting damage, which results in grooves in the raceways of (multiple) bearings and out-of-roundness in the rolling elements. If left unchecked, this damage can progress beyond acceptable levels, potentially leading to failure and unplanned shutdown.

[0006] Furthermore, for many wind turbines, the lubricant in the generator bearings deteriorates differently in different regions due to varying weather patterns and applications. Relubrication is performed on a scheduled basis, so sometimes the lubricant may be discarded while it is still usable.

[0007] Therefore, this disclosure relates to systems and methods for addressing the aforementioned problems by analyzing the three-phase voltages and currents on the rotor side or line side to detect degradation and / or damage in the initial stage. Summary of the Invention

[0008] The aspects and advantages of this disclosure will be set forth in part in the description which follows, or may be apparent from the description, or may be learned by practice of this disclosure.

[0009] In one aspect, the present invention relates to a method for preventing damage to bearings in a generator. The generator is electrically connected to a power conversion assembly having a first converter connected to a second converter. The method includes monitoring one or more electrical signals of the power conversion assembly via a controller. The method also includes converting the electrical signals(s) ...

[0010] In an embodiment, the electrical signals may include current and / or voltage collected from the first converter. More specifically, in an embodiment, the generator may be part of a wind turbine power system. In such an embodiment, the first converter may be a rotor-side converter, and the second converter may be a line-side converter of the wind turbine power system. Furthermore, in such an embodiment, the current may be a three-phase rotor current, and the voltage may be a three-phase rotor voltage of the rotor-side converter or the line-side converter.

[0011] In another embodiment, converting (multiple) electrical signals to the frequency domain may include calculating a complex rotation vector of one or more electrical signals and a complex fast Fourier transform (FFT) of the complex rotation vector.

[0012] In another embodiment, determining the characteristics of the spectral components(s) in the frequency band may include calculating one or more peak amplitudes of the spectral components(s) in the frequency band and calculating one or more entropies of the spectral components(s) in the frequency band.

[0013] In an additional embodiment, comparing the characteristics of the multiple spectral components in the frequency band with the multiple thresholds may include comparing one or more entropies with an entropy threshold and comparing one or more peak amplitudes with an amplitude threshold.

[0014] In an embodiment, generating a fault signal or a baseline signal based on the comparison may include: generating a fault signal when one or more entropies exceed an entropy threshold; comparing one or more peak amplitudes with an amplitude threshold if one or more entropies are less than an entropy threshold; generating a fault signal when one or more peak amplitudes are less than an amplitude threshold; and generating a baseline signal when one or more entropies are less than an entropy threshold and one or more peak amplitudes are greater than an amplitude threshold.

[0015] In such an embodiment, an increase in one or more entropies and a decrease in one or more peak amplitudes indicate a deterioration in electrical discharge machining (EDM) damage in the bearing.

[0016] In a particular embodiment, determining the characteristics of (multiple) spectral components in a frequency band may include: calculating the location of one or more peak amplitudes of one or more spectral components in the frequency band; and using one or more spectral components in the frequency band to monitor changes in friction, wherein lubrication deterioration causes a gradual increase in friction and a change in the location of one or more peak amplitudes.

[0017] In an additional embodiment, comparing the characteristics of the spectral components in the frequency band with the baseline values ​​may include: generating a high-dimensional vector comprising multiple characteristics, the multiple characteristics including at least one characteristic; and comparing the high-dimensional vector with a baseline cluster comprising similar vectors from a baseline generator.

[0018] In another embodiment, control actions may include changing the operating setpoint of the generator or power conversion assembly, shutting down the generator, generating an alarm, arranging repairs, replacing at least one component of the generator, or any other suitable action.

[0019] In another aspect, this disclosure relates to a method for preventing damage to bearings in a generator of an electric power system. The electric power system has a power conversion component having a first converter coupled to a second converter. The power conversion component is electrically connected to the generator. The method includes monitoring one or more electrical signals of the power conversion component of the electric power system via a controller. Furthermore, the method includes calculating a complex rotating vector of the one or more electrical signals via the controller. Furthermore, the method includes calculating a complex fast Fourier transform (FFT) of the complex rotating vector via the controller. The method also includes extracting one or more spectral components in a frequency band around one or more known characteristic frequencies of the bearing via the controller. The method also includes calculating one or more peak amplitudes in the frequency band via the controller. Furthermore, the method includes calculating one or more entropies in the frequency band via the controller. Furthermore, the method includes comparing one or more entropies with an entropy threshold via the controller. Furthermore, the method includes generating a fault signal for the bearing via the controller when one or more entropies exceed the entropy threshold. If one or more entropies do not exceed the threshold, the method further includes comparing one or more peak amplitudes with an amplitude threshold via the controller. The method also includes generating a fault signal for the bearing via the controller when one or more peak amplitudes are less than the amplitude threshold. Furthermore, the method includes generating a baseline signal for the bearing via a controller when one or more entropies are less than an entropy threshold and one or more peak amplitudes are greater than an amplitude threshold. In response to the generation of a fault signal, the method includes implementing a control action via the controller. It should be understood that the method may also include any one or more of the features and / or steps described herein.

[0020] In another aspect, this disclosure relates to a wind turbine power system connected to a power grid. The wind turbine power system includes a generator having a rotor, a stator, and at least one bearing. The wind turbine power system also includes a power conversion assembly electrically connected to the generator. The power conversion assembly includes a rotor-side converter connected to a line-side converter. Furthermore, the wind turbine power system includes a controller configured to perform multiple operations, including but not limited to: monitoring one or more electrical signals from the power conversion assembly; converting the one or more electrical signals to the frequency domain; extracting one or more spectral components in a frequency band of the frequency domain surrounding one or more known characteristic frequencies of the bearing; determining at least one characteristic of the one or more spectral components in the frequency band; comparing at least one characteristic of the one or more spectral components in the frequency band with at least one baseline value; generating a fault signal or baseline signal for the bearing based on the comparison; and implementing control actions in response to the generation of a fault signal. It should be understood that the wind turbine power system may also include any one or more of the features described herein.

[0021] These and other features, aspects, and advantages of this disclosure will become more readily understood with reference to the following description and the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0022] Technical Solution 1. A method for preventing damage to bearings in a generator, the generator being electrically connected to a power conversion assembly having a first converter connected to a second converter, the method comprising: One or more electrical signals of the power conversion component are monitored via a controller; The controller converts the one or more electrical signals to the frequency domain; One or more spectral components in the frequency band of the frequency domain surrounding one or more known characteristic frequencies of the bearing are extracted via the controller; The controller determines at least one characteristic of the one or more spectral components in the frequency band; The controller compares at least one characteristic of one or more spectral components in the frequency band with at least one baseline value. The controller generates a fault signal or baseline signal for the bearing based on the comparison; and In response to the generation of the fault signal, a control action is performed via the controller.

[0023] Technical Solution 2. The method according to Technical Solution 1, wherein the one or more electrical signals include at least one of current or voltage collected from the first converter.

[0024] Technical Solution 3. The method according to Technical Solution 2, wherein the generator is part of a wind turbine power system, the first converter is a rotor-side converter of the wind turbine power system, and the second converter is a line-side converter of the wind turbine power system, and wherein the current includes three-phase rotor current, and the voltage includes three-phase rotor voltage of the rotor-side converter or the line-side converter.

[0025] Technical Solution 4. The method according to Technical Solution 1, wherein converting the one or more electrical signals to the frequency domain further includes: Calculate the complex rotation vector of the one or more electrical signals; and Calculate the complex fast Fourier transform (FFT) of the complex rotation vector.

[0026] Technical Solution 5. The method according to Technical Solution 1, wherein determining the at least one characteristic of the one or more spectral components in the frequency band further includes: Calculate one or more peak amplitudes of the one or more spectral components in the frequency band; and Calculate one or more entropies of the one or more spectral components in the frequency band.

[0027] Technical Solution 6. The method according to Technical Solution 5, wherein comparing the at least one characteristic of the one or more spectral components in the frequency band with the at least one baseline value further includes: Compare the one or more entropies with an entropy threshold; and The one or more peak amplitudes are compared with amplitude thresholds.

[0028] Technical Solution 7. The method according to Technical Solution 6, wherein generating the fault signal or the baseline signal based on the comparison further includes: When one or more entropies exceed the entropy threshold, the fault signal is generated; If the one or more entropies are less than the entropy threshold, then the one or more peak amplitudes are compared with the amplitude threshold; The fault signal is generated when the amplitude of one or more peak values ​​is less than the amplitude threshold; and The baseline signal is generated when one or more entropies are less than the entropy threshold and one or more peak amplitudes are greater than the amplitude threshold.

[0029] Technical Solution 8. The method according to Technical Solution 7, wherein a change in at least one of the one or more entropies or the one or more peak amplitudes indicates a deterioration of electrical discharge machining (EDM) damage in the bearing.

[0030] Technical Solution 9. The method according to Technical Solution 1, wherein determining the at least one characteristic of the one or more spectral components in the frequency band further includes: Calculate the location of one or more peak amplitudes of the one or more spectral components in the frequency band; and The changes in friction are monitored using one or more spectral components in the frequency band. Deteriorated lubrication leads to a gradual increase in friction and a change in the location of the one or more peak amplitudes.

[0031] Technical Solution 10. The method according to Technical Solution 1, wherein comparing the at least one characteristic of the one or more spectral components in the frequency band with the at least one baseline value further includes: Generate a high-dimensional vector comprising multiple characteristics, wherein the multiple characteristics include at least one characteristic; and The high-dimensional vector is compared with a cluster of baselines that includes similar vectors from the baseline generator.

[0032] Technical Solution 11. The method according to Technical Solution 1, wherein the control action further includes changing the operating setpoint of the generator or the power conversion component, shutting down the generator, generating an alarm, arranging repair or replacement of at least one component of the generator.

[0033] Technical Solution 12. A method for preventing damage to bearings in a generator of an electric power system, the electric power system having a power conversion assembly having a first converter connected to a second converter, the power conversion assembly being electrically connected to the generator, the method comprising: One or more electrical signals of the power conversion components of the power system are monitored via a controller; The controller calculates the complex rotation vector of the one or more electrical signals; The complex fast Fourier transform (FFT) of the complex rotation vector is calculated via the controller; One or more spectral components in a frequency band surrounding one or more known characteristic frequencies of the bearing are extracted via the controller; The controller calculates one or more peak amplitudes in the frequency band; The controller calculates one or more entropies in the frequency band; The controller compares the one or more entropies with an entropy threshold. When one or more entropies exceed the entropy threshold, a fault signal for the bearing is generated via the controller; If the one or more entropies do not exceed the threshold, then the one or more peak amplitudes are compared with the amplitude threshold via the controller; When the amplitude of one or more peak values ​​is less than the amplitude threshold, the controller generates the fault signal for the bearing. When the one or more entropies are less than the entropy threshold and the one or more peak amplitudes are greater than the amplitude threshold, a baseline signal for the bearing is generated via the controller; and In response to the generation of the fault signal, a control action is performed via the controller.

[0034] Technical Solution 13. A wind turbine power system connected to a power grid, the wind turbine power system comprising: A doubly fed induction generator (DFIG) includes a rotor, a stator, and at least one bearing; A power conversion assembly electrically connected to the DFIG, the power conversion assembly including a rotor-side converter connected to a line-side converter; A controller configured to control the wind turbine power system, the controller being configured to perform a plurality of operations, the plurality of operations including: Monitor one or more electrical signals of the power conversion component; Convert the one or more electrical signals to the frequency domain; Extract one or more spectral components from the frequency band of the frequency domain surrounding one or more known characteristic frequencies of the bearing; Determine at least one characteristic of the one or more spectral components in the frequency band; Compare at least one characteristic of the one or more spectral components in the frequency band with at least one baseline value; Based on the comparison, a fault signal or baseline signal for the bearing is generated; and In response to the generation of the fault signal, a control action is performed.

[0035] Technical Solution 14. The wind turbine power system according to Technical Solution 13, wherein the one or more electrical signals include at least one of current or voltage collected from the rotor-side converter or the line-side converter.

[0036] Technical Solution 15. The wind turbine power system according to Technical Solution 13, wherein converting the one or more electrical signals to the frequency domain further includes: Calculate the complex rotation vector of the one or more electrical signals; and Calculate the complex fast Fourier transform (FFT) of the complex rotation vector.

[0037] Technical Solution 16. The wind turbine power system according to Technical Solution 13, wherein determining the at least one characteristic of the one or more spectral components in the frequency band further includes: Calculate one or more peak amplitudes of the one or more spectral components in the frequency band; and Calculate one or more entropies of the one or more spectral components in the frequency band.

[0038] Technical Solution 17. The wind turbine power system according to Technical Solution 16, wherein comparing the at least one characteristic of the one or more spectral components in the frequency band with the at least one baseline value further includes: Compare the one or more entropies with an entropy threshold; and The one or more peak amplitudes are compared with amplitude thresholds.

[0039] Technical Solution 18. The wind turbine power system according to Technical Solution 17, wherein generating the fault signal or the baseline signal for the bearing based on the comparison further includes: When one or more entropies exceed the entropy threshold, the fault signal is generated; If the one or more entropies are less than the entropy threshold, then the one or more peak amplitudes are compared with the amplitude threshold; The fault signal is generated when the amplitude of one or more peak values ​​is less than the amplitude threshold; and The baseline signal is generated when one or more entropies are less than the entropy threshold and one or more peak amplitudes are greater than the amplitude threshold.

[0040] Technical Solution 19. The wind turbine power system according to Technical Solution 18, wherein determining the at least one characteristic of the one or more spectral components in the frequency band further includes: Calculate the location of one or more peak amplitudes of the one or more spectral components in the frequency band; and The changes in friction are monitored using one or more spectral components in the frequency band. Deteriorated lubrication leads to a gradual increase in friction and a change in the location of the one or more peak amplitudes.

[0041] Technical Solution 20. The wind turbine power system according to Technical Solution 13, wherein comparing the at least one characteristic of the one or more spectral components in the frequency band with the at least one baseline value further includes: Generate a high-dimensional vector comprising multiple characteristics, wherein the multiple characteristics include at least one characteristic; and The high-dimensional vector is compared with a cluster of baselines that includes similar vectors from the baseline generator. Attached Figure Description

[0042] The complete and implementable disclosure of this disclosure, including its best mode, is set forth in the description with reference to the accompanying drawings, in which: Figure 1 The illustration is a perspective view of a portion of an embodiment of a wind turbine according to the present disclosure; Figure 2 The diagram is suitable for use with Figure 1 A schematic diagram of one embodiment of an electric power system used in conjunction with a wind turbine shown in the diagram; Figure 3 The diagram is suitable for use with Figure 1 A block diagram of one embodiment of a controller used with the wind turbine shown in the figure; Figure 4 The figure is a simplified schematic diagram of an embodiment of a variable frequency drive (VFD) that maintains a constant electrical frequency output on the grid side of a generator according to the present disclosure; Figure 5 The figure is a cross-sectional schematic diagram of one embodiment of the generator according to the present disclosure, and in particular illustrates the grounding brush in contact with the rotor of the generator; Figure 6 The figure shows a flowchart of an embodiment of a method for preventing damage to the bearings of a generator due to EDM, according to the present disclosure; Figure 7 The figure shows a flowchart of another embodiment of a method for preventing damage to the bearings of a generator due to EDM, according to the present disclosure; Figure 8 The figure is a graphical representation of the effect of EDM on the current spectrum in a generator according to this disclosure; Figure 9 The figure shows a flowchart of yet another embodiment of the method for preventing damage to bearings in a generator according to the present disclosure; Figure 10 The figure shows a graphical representation of the effect of lubricant degradation on the current spectrum in a generator according to this disclosure; and Figure 11 The figure shows a flowchart of another embodiment of the method for preventing damage to the bearings of a generator according to the present disclosure. Detailed Implementation

[0043] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the present disclosure and not as a limitation thereof. Indeed, it will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from the scope or spirit thereof. For example, a feature illustrated or described in part as one embodiment may be used with another embodiment to produce yet another embodiment. Therefore, it is intended that the present disclosure cover such modifications and variations and their equivalents as fall within the scope of the appended claims.

[0044] Generally, the present invention relates to systems and methods for preventing damage to bearings in electric power systems (such as wind turbine power systems) and / or lubricant deterioration, including generators (such as DFIGs, permanent magnet generators (PMGs), or any other motors). Specifically, in embodiments, three-phase currents and voltages injected by a rotor-side (or line-side) inverter can be analyzed to calculate FFT components around one or more known bearing characteristic frequencies. For EDM damage, the entropy and peak values ​​of these frequency bands can be calculated, and cluster variations in high-dimensional space can be assessed. Statistical deviations from baseline clusters (such as a gradual increase in entropy and a decrease in peak amplitude) indicate worsening of EDM damage. When lubricant deterioration is present, a gradual increase in friction and a change in the location of frequency peaks can be observed in the three-phase currents and voltages. Therefore, tracking the location of these peaks and / or general deviations from the baseline in a multivariate cluster analysis scenario provides a means for trend analysis of such data for bearing health metrics and for estimating the remaining useful life (RUL) of the bearing. As used herein, a baseline cluster may include a set of features corresponding to several data files captured from a generator under test, for example, around any particular time period or extended to a longer time period if necessary. Furthermore, in embodiments, the baseline cluster may relate to features calculated from different machines of similar class / design installed in different locations.

[0045] Accordingly, this disclosure offers numerous advantages not found in the prior art. For example, the systems and methods of this disclosure enable bearing diagnostics without requiring any separate sensors for measuring vibration or temperature. Instead, as mentioned, the systems and methods of this disclosure use inverter electrical signals for bearing diagnostics. Furthermore, in embodiments, the systems and methods of this disclosure detect EDM damage and / or lubricant degradation in an initial stage before such damage begins to appear in sensor data. As an example, the systems and methods of this disclosure can estimate the health of the grounding brush through spectral analysis of the current and can detect damage using entropy increase. Moreover, the systems and methods of this disclosure can perform high-fidelity bearing failure detection using frequencies other than the known characteristic bearing frequencies. Therefore, intelligent scheduling of maintenance and / or repair activities can be employed.

[0046] Now refer to the attached diagram, Figure 1 The illustration shows a perspective view of one embodiment of a wind turbine 100 according to a portion of the present disclosure, configured to implement the methods described herein. The wind turbine 100 includes a nacelle 102 that typically houses a generator (not shown). The nacelle 102 is mounted on a tower 104 having any suitable height conducive to the operation of the wind turbine 100 as described herein. The wind turbine 100 also includes a rotor 106 comprising three blades 108 attached to a rotating hub 110. Alternatively, the wind turbine 100 may include any number of blades 108 conducive to the operation of the wind turbine 100 as described herein.

[0047] Now for reference Figure 2 The diagram illustrates a schematic representation of an embodiment of an electric power subsystem 200 that can be used with a wind turbine 100. Furthermore, the wind turbine 10 and the electric power system 200 are collectively referred to herein as a wind turbine power system 150. Thus, during operation of the wind turbine power system 150, wind impacts the blades 108, and the blades 108 convert wind energy into mechanical rotational torque, which rotatably drives a low-speed shaft 112 (also referred to herein as a rotor shaft) via a hub 110. The low-speed shaft 112 is configured to drive a gearbox 114, which then increases the low rotational speed of the low-speed shaft 112 to drive a high-speed shaft 116 (also referred to herein as a generator shaft) at an increased rotational speed. The high-speed shaft 116 is generally rotatably coupled to a generator 118 to rotatably drive a generator having a field winding 125 (…). Figure 5 ) generator rotor 122.

[0048] In one embodiment, generator 118 may be a wound-rotor, three-phase, doubly-fed induction (asynchronous) generator (DFIG) including a generator stator 120 magnetically coupled to generator rotor 122. Accordingly, a rotating magnetic field can be induced by generator rotor 122, and voltage can be induced within generator stator 120 magnetically coupled to generator rotor 122. In one embodiment, generator 118 is configured to convert rotational mechanical energy into a sinusoidal three-phase alternating current (AC) electrical signal in generator stator 120. The associated electrical power can be transmitted to main transformer 234 via stator bus 208, stator synchronizing switch 206, system bus 216, main transformer circuit breaker 214, and generator-side bus 236. Main transformer 234 increases the voltage amplitude of the electrical power so that the converted electrical power can be further transmitted to the power grid via grid circuit breaker 238, circuit breaker-side bus 240, and grid bus 242.

[0049] Furthermore, the electric power system 200 may include a controller 202 configured to control any components of the wind turbine 100 and / or implement the steps described herein. For example, as Figure 3 Specifically, as shown herein, controller 202 may include one or more processors 204 and(multiple) associated memory devices 207 configured to perform various computer-implemented functions (e.g., performing methods, steps, calculations, etc., as disclosed herein and storing related data). Additionally, controller 202 may also include a communication module 209 to facilitate communication between controller 202 and various components of wind turbine 100 (e.g., ...). Figure 2 Communication between any of the components. Furthermore, the communication module 209 may include a sensor interface 211 (e.g., one or more analog-to-digital converters) to allow signals transmitted from one or more sensors to be converted into signals that can be understood and processed by the processor 204. It should be appreciated that sensors (e.g., sensors 252, 254, 256, 258) can be communicatively coupled to the communication module 209 using any suitable means. For example, as Figure 3 As shown, sensors 252, 254, 256, and 258 can be connected to sensor interface 211 via a wired connection. However, in other embodiments, sensors 252, 254, 256, and 258 can be connected to sensor interface 211 via a wireless connection, such as by using any suitable wireless communication protocol known in the art. Accordingly, processor 204 can be configured to receive one or more signals from the sensors.

[0050] As used herein, the term "processor" refers not only to integrated circuits known in the art as contained in a computer, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and other programmable circuits. Processor 204 is also configured to compute advanced control algorithms and transmit them to various Ethernet or serial-based protocols (Modbus, OPC, CAN, etc.). Additionally, the memory device(s) 207 may generally include memory elements(s), 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, compact disc read-only memory (CD-ROM), magneto-optical disks (MOD), digital versatile discs (DVDs), and / or other suitable memory elements. Such memory devices 207 may be generally configured to store suitable computer-readable instructions, which, when implemented by processor(s) 204, configure controller 202 to perform various functions as described herein.

[0051] Re-reference Figure 2The generator stator 120 may be electrically connected to the stator synchronizing switch 206 via stator bus 208. In one embodiment, the generator rotor 122 may be electrically connected to the bidirectional power conversion assembly 210 or power converter via rotor bus 212. Alternatively, the generator rotor 122 may be electrically connected to the rotor bus 212 via any other means that facilitates the operation of the electrical power system 200 as described herein. In another embodiment, the stator synchronizing switch 206 may be electrically connected to the main transformer circuit breaker 214 via system bus 216.

[0052] Power conversion assembly 210 may include a first converter and a second converter. For example, as shown, the first converter may be a rotor-side converter 220, and the second converter 22 may be a line-side converter 222. Furthermore, as shown, power conversion assembly 210 may include a rotor filter 218 electrically connected to the generator rotor 122 via a rotor bus 212. Additionally, the rotor filter 218 may include a rotor-side reactor. A rotor filter bus 219 electrically connects the rotor filter 218 to the rotor-side power converter 220. Furthermore, the rotor-side power converter 220 may be electrically connected to the line-side power converter 222 via a single DC link 244. Alternatively, the rotor-side power converter 220 and the line-side power converter 222 may be electrically connected via separate and independent DC links. Furthermore, as shown, the DC link 244 may include a positive rail 246, a negative rail 248, and at least one capacitor 250 connected between them.

[0053] Furthermore, the line-side power converter bus 223 can electrically connect the line-side power converter 222 to the line filter 224. Additionally, the line bus 225 can electrically connect the line filter 224 to the line contactor 226. Furthermore, the line filter 224 may include a line-side reactor. Furthermore, the line contactor 226 can be electrically connected to the transfer circuit breaker 228 via the transfer circuit breaker bus 230. Furthermore, the transfer circuit breaker 228 can be electrically connected to the main transformer circuit breaker 214 via the system bus 216 and the connection bus 232. The main transformer circuit breaker 214 can be electrically connected to the main power transformer 234 via the generator-side bus 236. The main transformer 234 can be electrically connected to the grid circuit breaker 238 via the circuit breaker-side bus 240. The grid circuit breaker 238 can be connected to the power transmission and distribution grid via the grid bus 242.

[0054] Special reference Figure 2 and Figure 4The alternating current (AC) power generated at the generator stator 120 by the rotation of rotor 106 is provided to the grid bus 242 via a dual path. The dual path is defined by stator bus 208 and rotor bus 212. On the rotor bus side 212, sinusoidal multiphase (e.g., three-phase) AC power is provided to power conversion component 210. Rotor-side power converter 220 converts the AC power provided from rotor bus 212 into DC power and provides the DC power to DC link 244. Switching elements 245 (e.g., IGBTs) used in the bridge circuit of rotor-side power converter 220 can be modulated to convert the AC power provided from rotor bus 212 into DC power suitable for DC link 244.

[0055] Line-side converter 222 converts DC power on DC link 244 into AC output power suitable for electrical grid bus 242. Specifically, the switching element 247 (e.g., IGBT) used in the bridge circuit of line-side power converter 222 can be modulated to convert DC power on DC link 244 into AC power on line-side bus 225. AC power from power conversion assembly 210 can be combined with power from stator 120 to provide multiphase power (e.g., three-phase power) with a frequency substantially maintained at the frequency of electrical grid bus 242 (e.g., 50Hz / 60Hz).

[0056] It should be understood that the rotor-side power converter 220 and the line-side power converter 222 can have any configuration using any switching devices that facilitate the operation of the power system 200 as described herein. For example, Figure 4 A simplified schematic diagram of one embodiment of a variable frequency drive (VFD) that maintains a constant electrical frequency output on the grid side of generator 118 is illustrated. As shown, the VFD configuration includes a six-switch voltage source rectifier on the rotor-side converter 220, a DC link capacitor 244 to minimize DC voltage variations, and a six-switch voltage source inverter utilizing pulse width modulation on the grid side. The rotor-side switching element 245 is typically a diode or a silicon controlled rectifier (SCR), while the grid-side switching element 247 is typically an insulated-gate bipolar transistor (IGBT). Accordingly, the amplitude and frequency of the current supplied to generator rotor 122 via the VFD can be varied to account for variations in rotor shaft speed and maintain a constant output on the generator stator windings.

[0057] Furthermore, the power conversion assembly 210 may be electronically data-communication connected to the controller 202 and / or a separate or integrated converter controller 262 to control the operation of the rotor-side power converter 220 and the line-side power converter 222. For example, during operation, the controller 202 may be configured to receive one or more voltage and / or current measurement signals from a first set of voltage and current sensors 252. Thus, the controller 202 may be configured to monitor and control at least some of the operating variables associated with the wind turbine 100 via the sensors 252. In the illustrated embodiment, each of the sensors 252 may be electrically connected to each of the three phases of the power grid bus 242. Alternatively, the sensors 252 may be electrically connected to any part of the power system 200 that facilitates the operation of the power system 200 as described herein. In addition to the sensors described above, the sensors may also include a second set of voltage and current sensors 254, a third set of voltage and current sensors 256, and a fourth set of voltage and current sensors 258 (all in...). Figure 2 (as shown in the diagram) and / or any other suitable sensor.

[0058] It should also be understood that any number or type of voltage and / or current sensors 252, 254, 256, 258 may be used within the wind turbine 100 and at any location. For example, the sensors may be current transformers, shunt sensors, Rogowski coils, Hall effect current sensors, micro inertial measurement units (MIMUs) or the like, and / or any other suitable voltage or current sensors now known or hereafter developed in the art.

[0059] Therefore, converter controller 262 is configured to receive one or more voltage and / or current feedback signals from sensors 252, 254, 256, and 258. More specifically, in some embodiments, the current or voltage feedback signal may include at least one of a line feedback signal, a line-side converter feedback signal, a rotor-side converter feedback signal, or a stator feedback signal. For example, as shown in the illustrated embodiment, converter controller 262 receives voltage and current measurement signals from a second set of voltage and current sensors 254 electronically data-communicated with stator bus 208. Converter controller 262 may also receive third and fourth sets of voltage and current measurement signals from a third set of voltage and current sensors 256 and a fourth set of voltage and current sensors 258. Furthermore, converter controller 262 may be configured to have any of the features described herein with respect to main controller 202. Accordingly, converter controller 262 is configured to implement the various method steps described herein and may be configured to be similar to controller 202.

[0060] Now for reference Figure 5 and Figure 6 Various diagrams are provided to further describe the systems and methods of this disclosure. For example, Figure 5A perspective cross-sectional view of one embodiment of the generator 118 of this disclosure is illustrated, particularly showing a plurality of brushes 126 configured with its rotor 122; and Figure 6 The illustration shows a flowchart of an embodiment of a method 300 for preventing damage to the bearings (such as bearing 124) of a generator 118 in an electric power system 200.

[0061] In particular, such as Figure 5 As shown, generator 118 may generally include a bearing housing 130 for accommodating generator stator 120 and generator rotor 122. Furthermore, as shown, generator rotor 122 includes a field winding 125 or coil. Additionally, as shown, bearing housing 130 also generally includes bearing insulation 132 arranged circumferentially around the field winding 125. Furthermore, generator 118 may also include one or more bearings 124 rotatably mounted in a high-speed shaft 116. Additionally, generator 118 may include one or more generator slip rings 128 fixedly connected to one or more brushes 126.

[0062] Therefore, during wind turbine operation, a voltage is typically induced on the high-speed shaft 116 due to the capacitive coupling between the generator rotor 122 and stator 120. This capacitive coupling is directly related to VFD operation because the voltage change over time (dv / dt) causes the capacitive coupling. Furthermore, the asymmetry of the generator's magnetic field can also cause a shaft voltage on the high-speed shaft 116. Under normal operating conditions, the current driven by this induced shaft voltage is safely dissipated through brushes 126. Generally, such brushes 126 act as sliding contacts between rotating slip rings and stationary busbars.

[0063] Furthermore, such brushes 126 are typically made of graphite / metal composite, pressed into rectangular strips, and typically mounted on the non-driving end of the generator 118. It should be understood that the generator 118 may include any suitable number of brushes 126, particularly including at least one brush. Additionally, as... Figure 5As shown, brush 126 can be mounted perpendicular to the high-speed shaft 116. Alternatively, brush 126 can have any other suitable mounting configuration relative to the generator rotor 122. Accordingly, some of the brushes 126 can be used to draw AC voltage from at least one of the generator slip rings 128, while the remaining(s) of brush(s) act as controlled paths to ground (i.e., grounding brushes). Furthermore, as shown, brush 126 can be positioned radially outward of the generator slip ring(s) 128, with consecutive brushes in each group mounted at 60 to 120-degree intervals. Additionally, each brush 126 can be rigidly fixed in its axial position to minimize deflection under normal operating loads. The brush holder may also use a constant-pressure helical spring to maintain contact between the brush(s) 126 and the generator slip ring(s) 128. A microswitch may also be mounted at the bottom of the brush holder to trigger a warning signal when the brushes wear excessively.

[0064] Accordingly, the grounding brush 126 may be sized and oriented to engage the generator rotor 122 to facilitate providing an electrical connection from the generator rotor 122 to ground (not shown). Therefore, the grounding brush 126 is configured to protect the generator bearing 124 and all other components of the generator 118 from harmful voltages and currents. More specifically, the grounding brush 126 is configured to provide a low-impedance path around the bearing 124.

[0065] When the generator grounding system is damaged (i.e., the grounding brush 126 loses contact with the corresponding generator slip ring 128 and / or the bearing insulation 132 becomes damaged), excessive voltage accumulates on the high-speed shaft 116. This shaft voltage drives current to find the path of lowest impedance to ground. In the case of DFIG, this path passes through the bearing housing 130. More specifically, the high-speed shaft 116 will accumulate voltage first. If the grounding system is damaged (i.e., the grounding brush 126 is lifted), all components connected to or coupled to the generator rotor 122 will also begin to accumulate voltage. Due to the presence of lubricating oil, the outer ring raceway is where most of the discharge occurs. Oil has a low dielectric capacity and decomposes faster than the surrounding air or other dielectric materials. Once the voltage exceeds the dielectric capacity of the lubricating oil in the bearing, it pulses and discharges, causing an arc. This cycle repeats as long as the grounding brush 126 is lifted, leading to pitting and trenching corrosion of the bearing raceway, ultimately causing bearing failure. Furthermore, the aforementioned problems also lead to damage to the bearing insulation 132.

[0066] Accordingly, this disclosure aims to prevent bearing damage such as EDM damage. More specifically, as Figure 6 The diagram shows a flowchart of one embodiment of a method 300 for preventing damage to bearings (such as bearing 124) of a generator 118 due to EDM. Generally, method 300 is referred to herein with reference to... Figures 1 to 5The wind turbine 10, electric power system 200, controller 202, and generator 118 are described in the diagram. However, it should be appreciated that the disclosed method 300 can be implemented using an electric power system with any other suitable configuration. Furthermore, although for illustrative and discussion purposes, Figure 6 The steps are described in a specific order, but the methods discussed herein are not limited to any particular order or arrangement. Those skilled in the art will recognize, using the disclosure provided herein, that the various steps of the methods disclosed herein can be omitted, rearranged, combined, and / or modified in various ways without departing from the scope of this disclosure.

[0067] As shown at (302), method 300 includes monitoring one or more electrical signals of the power conversion component 210 via a controller (such as controller 202). For example, in an embodiment, the operating parameters may include current and / or voltage collected from the rotor-side power converter 220 or the line-side converter 222. More specifically, Figure 7 The detailed method 400 is illustrated, as shown at (402), which includes collecting three-phase current and / or three-phase voltage (I0) from the rotor-side power converter 220. A I B and I C ).

[0068] Re-reference Figure 6 As shown at (304), method 300 includes converting (a plurality of) electrical signals to the frequency domain via controller 202. More specifically, as shown in Figure 7 As shown at (404), controller 202 is configured to convert one or more electrical signals to the frequency domain by, for example, calculating the complex rotation vector of one or more electrical signals using the following equation (1): in, It is a complex number representing a 120-degree phase shift, and , and They are phases , and The instantaneous current in. It is a complex vector of instantaneous current.

[0069] In addition, such as in Figure 7 As shown at (406), the controller 202 also calculates the complex fast Fourier transform (FFT) of the complex rotation vector.

[0070] refer to Figure 6 and Figure 7As shown at (306), method 300 therefore includes extracting one or more spectral components in a frequency band of a frequency domain surrounding one or more known characteristic frequencies of the bearing 124 via controller 202. Thus, as in Figure 7 As shown at (405), the controller 202 is also configured to calculate the bearing characteristic frequency for bearing size and / or dimensions.

[0071] Therefore, as in Figure 6 As shown at (308), method 300 further includes determining at least one characteristic of the spectral components(s) in the frequency band via controller 202. More specifically, as in Figure 7 As shown at (408), controller 202 can calculate one or more peak amplitudes of the spectral components(s) in the frequency band. Furthermore, as shown at (410), controller can also calculate one or more entropies of the spectral components(s) in the frequency band.

[0072] As shown at (310), method 300 includes comparing (multiple) characteristics of (multiple) spectral components in a frequency band with at least one baseline value via controller 202. More specifically, as shown in Figure 7 As shown at (412) and (414), in one embodiment, controller 202 is configured to compare one or more entropies with an entropy threshold and one or more peak amplitudes with an amplitude threshold, respectively. In some embodiments, as an example, the following equation (2) can be used to calculate the entropy: in, A i It is the first of the amplitude spectrum i Each component.

[0073] In an alternative embodiment, controller 202 may be configured to generate a high-dimensional vector comprising multiple characteristics and compare this high-dimensional vector with a baseline cluster having similar vectors from a baseline generator. In such an embodiment, the deviation from the baseline cluster provides a measure of the generator bearing health.

[0074] Furthermore, and re-reference Figure 6 As shown at (312), method 300 includes generating a fault signal or baseline signal for the bearing based on a comparison via controller 202. More specifically, as shown in Figure 7As shown at (416), controller 202 is configured to generate a fault signal when one or more entropies exceed an entropy threshold. Conversely, if one or more entropies are less than the entropy threshold, as shown at (414), controller 202 is configured to compare one or more peak amplitudes with an amplitude threshold. Furthermore, as shown at (416), controller 202 is configured to generate a fault signal when one or more peak amplitudes are less than an amplitude threshold. Additionally, as shown at (418), controller 202 is configured to generate a baseline signal when one or more entropies are less than the entropy threshold and one or more peak amplitudes are greater than the amplitude threshold.

[0075] In such an embodiment, an increase in one or more entropies and a decrease in one or more peak amplitudes indicate a worsening of EDM damage in the bearing. For example, as Figure 8 As shown, a graphical representation 500 illustrates the effect of the EDM according to this disclosure on the current spectrum in a generator. Specifically, as shown, graphical representation 500 depicts the frequency domains of the baseline bearing spectrum 502 and the faulty bearing spectrum 504. Thus, graphical representation 500 illustrates how the faulty bearing spectrum 504 has increased entropy and a lower peak amplitude than the baseline bearing spectrum 502.

[0076] Re-reference Figure 6 In response to the generation of a fault signal, as shown at (314), method 300 includes implementing control actions via controller 202. For example, in a particular embodiment, the control actions may include changing the operating setpoint of the wind turbine 10, shutting down the wind turbine 10, generating an alarm, arranging repairs, replacing at least one of bearing insulation 132 or grounding brush 126, and / or any other suitable actions.

[0077] Now for reference Figure 9 The diagram illustrates a flowchart of another embodiment of a method 600 for preventing damage in the bearings of a generator according to the present disclosure. As shown at (602), method 600 includes collecting three-phase current and / or three-phase voltage (e.g., I0) from rotor-side power converter 220 and / or line-side converter 222. A I B and I C Furthermore, as shown at (604), method 600 includes, for example, calculating a complex rotation vector of one or more electrical signals using the following equation (3): in, It is a complex number representing a 120-degree phase shift, and , and They are phases , and The instantaneous current in. It is a complex vector of instantaneous current. In addition to using the complex rotating vector of current as described above, this disclosure also covers the use of spectral information from other quantities derived from voltage and current, such as instantaneous active power, reactive power, etc., which can be used for PMG and / or other types of motors.

[0078] Furthermore, as shown at (606), method 600 includes calculating a complex FFT of the complex rotation vector. Therefore, as shown at (605), controller 202 is also configured to calculate the bearing characteristic frequency for bearing size and / or dimensions. As shown at (608), method 600 includes extracting spectral components in a frequency band surrounding the bearing characteristic frequency. As shown at (610), method 600 then monitors the peak amplitude of the spectral components and tracks the location of the peak amplitude in the frequency band surrounding the bearing characteristic frequency.

[0079] Therefore, as shown at (612), method 600 includes determining whether the peak position has changed. If so, then as shown at (614), controller 202 is configured to indicate that a frictional change has occurred in the bearing. If not, the method proceeds to (616) and determines whether the peak amplitude has changed. If so, then as shown at (618), controller 202 is configured to indicate that bearing damage has begun. If not, then as shown at (620), controller 202 is configured to indicate that the bearing represents the baseline generator (e.g., the bearing is healthy and / or can continue to operate as is).

[0080] Now for reference Figure 10 The figure illustrates a graphical representation 700 of the effect of lubricant degradation on the current spectrum in a generator according to the present disclosure. Specifically, as shown, graphical representation 700 depicts the frequency domain of the spectral components in the bearing's frequency band. More specifically, as shown, graphical representation 700 illustrates arrow 702, which describes the increase in characteristic frequencies under conditions of improved lubricant health.

[0081] Figure 11A flowchart of yet another embodiment of a method 800 for preventing damage in the bearings of a generator according to this disclosure is illustrated. As shown, graph 802 illustrates the frequency component shifts of a baseline 804 and a fault 806 for the same generator speed and compares the entropy of healthy and faulty components. Thus, as shown at (808), method 800 calculates the peak amplitude and angle of each of the healthy and faulty components. As shown at (810), method 800 includes estimating the anomalous level of the peak. As shown at (812), method 800 includes determining whether the peak is sufficiently high. If so, then as shown at (814) and (816), method 800 includes considering the spectrum around the peak and determining its entropy. If not, then as shown at (818) and (820), method 800 includes considering the entire spectrum and determining its entropy.

[0082] Various aspects and embodiments of the present invention are defined by the following numbered clauses: Clause 1. A method for preventing damage to bearings in a generator electrically connected to a power conversion assembly having a first converter connected to a second converter, the method comprising: One or more electrical signals of the power conversion components are monitored via the controller; One or more electrical signals are converted to the frequency domain via a controller; One or more spectral components in the frequency band of the frequency domain surrounding one or more known characteristic frequencies of the bearing are extracted via the controller; Determine at least one characteristic of one or more spectral components in a frequency band via a controller; The controller compares at least one characteristic of one or more spectral components in the frequency band with at least one baseline value. The controller generates a fault signal or baseline signal for the bearing based on this comparison; and In response to the generation of a fault signal, a control action is implemented via the controller.

[0083] Clause 2. The method according to any of the preceding clauses, wherein one or more electrical signals include at least one of current or voltage collected from the first converter.

[0084] Clause 3. The method according to any of the preceding clauses, wherein the generator is part of a wind turbine power system, the first converter is a rotor-side converter of the wind turbine power system, and the second converter is a line-side converter of the wind turbine power system, and wherein the current includes three-phase rotor current, and the voltage includes three-phase rotor voltage of the rotor-side converter or the line-side converter.

[0085] Clause 4. The method according to any of the preceding clauses, wherein converting one or more electrical signals to the frequency domain further comprises: Calculate the complex rotation vector of one or more electrical signals; and Calculate the complex fast Fourier transform (FFT) of a complex rotating vector.

[0086] Clause 5. The method according to any of the preceding clauses, wherein determining at least one characteristic of one or more spectral components in the frequency band further comprises: Calculate the peak amplitude of one or more spectral components in a frequency band; and Calculate one or more entropies of one or more spectral components in a frequency band.

[0087] Clause 6. The method according to any of the preceding clauses, wherein comparing at least one characteristic of one or more spectral components in the frequency band with at least one baseline value further comprises: Compare one or more entropies with an entropy threshold; and Compare one or more peak amplitudes with an amplitude threshold.

[0088] Clause 7. The method according to any of the preceding clauses, wherein generating a fault signal or baseline signal based on the comparison further comprises: A fault signal is generated when one or more entropies exceed the entropy threshold. If one or more entropies are less than the entropy threshold, then the amplitude of one or more peaks is compared with the amplitude threshold. A fault signal is generated when one or more peak amplitudes are less than the amplitude threshold; and A baseline signal is generated when one or more entropies are less than an entropy threshold and one or more peak amplitudes are greater than an amplitude threshold.

[0089] Clause 8. The method according to any of the preceding clauses, wherein a change in at least one of one or more entropies or one or more peak amplitudes indicates a deterioration of electrical discharge machining (EDM) damage in the bearing.

[0090] Clause 9. The method according to any of the preceding clauses, wherein determining at least one characteristic of one or more spectral components in the frequency band further comprises: Calculate the location of one or more peak amplitudes of one or more spectral components within a frequency band; and Use one or more spectral components in the frequency band to monitor changes in friction. Among these factors, deteriorated lubrication leads to a gradual increase in friction and a change in the location of one or more peak amplitudes.

[0091] Clause 10. The method according to any of the preceding clauses, wherein comparing at least one characteristic of one or more spectral components in the frequency band with at least one baseline value further comprises: Generate a high-dimensional vector comprising multiple properties, wherein at least one property is included; and The high-dimensional vector is compared with a baseline cluster that includes similar vectors from the baseline generator.

[0092] Clause 11. The method according to any of the preceding clauses, wherein the control action further includes changing the operating setpoint of the generator or power conversion assembly, shutting down the generator, generating an alarm, arranging repair or replacement of at least one component of the generator.

[0093] Clause 12. A method for preventing damage to bearings in a generator of an electric power system having a power conversion assembly having a first converter coupled to a second converter, the power conversion assembly being electrically coupled to a generator, the method comprising: One or more electrical signals of the power conversion components of the power system are monitored via a controller; The controller calculates a complex rotation vector of one or more electrical signals; The complex fast Fourier transform (FFT) of the complex rotation vector is calculated via the controller; One or more spectral components in a frequency band surrounding one or more known characteristic frequencies of the bearing are extracted via a controller; The controller calculates one or more peak amplitudes in the frequency band. Calculate one or more entropies in the frequency band via the controller; The controller compares one or more entropies with an entropy threshold. When one or more entropies exceed the entropy threshold, a fault signal for the bearing is generated via the controller; If one or more entropies do not exceed a threshold, then the controller compares one or more peak amplitudes with the amplitude threshold. When one or more peak amplitudes are less than the amplitude threshold, a fault signal for the bearing is generated via the controller; When one or more entropies are less than an entropy threshold and one or more peak amplitudes are greater than an amplitude threshold, a baseline signal for the bearing is generated via the controller; and In response to the generation of a fault signal, a control action is implemented via the controller.

[0094] Clause 13. A wind turbine power system connected to a power grid, the wind turbine power system comprising: A doubly fed induction generator (DFIG) includes a rotor, a stator, and at least one bearing; A power conversion assembly electrically connected to a DFIG, the power conversion assembly including a rotor-side converter connected to a line-side converter; A controller configured to control a wind turbine power system, the controller being configured to perform a plurality of operations, the plurality of operations including: Monitor one or more electrical signals of the power conversion components; Convert one or more electrical signals to the frequency domain; Extract one or more spectral components from the frequency band of the frequency domain surrounding one or more known characteristic frequencies of the bearing; Determine at least one characteristic of one or more spectral components in a frequency band; Compare at least one characteristic of one or more spectral components in the frequency band with at least one baseline value; This comparison is used to generate a fault signal or baseline signal for the bearing; and In response to the generation of a fault signal, a control action is performed.

[0095] Clause 14. The wind turbine power system according to Clause 13, wherein one or more electrical signals include at least one of current or voltage collected from a rotor-side converter or a line-side converter.

[0096] Clause 15. The wind turbine power system according to Clauses 13 to 14, wherein converting one or more electrical signals to the frequency domain further includes: Calculate the complex rotation vector of one or more electrical signals; and Calculate the complex fast Fourier transform (FFT) of a complex rotating vector.

[0097] Clause 16. The wind turbine power system according to Clauses 13 to 15, wherein determining at least one characteristic of one or more spectral components in the frequency band further includes: Calculate the peak amplitude of one or more spectral components in a frequency band; and Calculate one or more entropies of one or more spectral components in a frequency band.

[0098] Clause 17. The wind turbine power system according to Clauses 13 to 16, wherein comparing at least one characteristic of one or more spectral components in the frequency band with at least one baseline value further includes: Compare one or more entropies with an entropy threshold; and Compare one or more peak amplitudes with an amplitude threshold.

[0099] Clause 18. The wind turbine power system as described in Clauses 13 to 17, wherein generating a fault signal or baseline signal for the bearing based on the comparison further includes: A fault signal is generated when one or more entropies exceed the entropy threshold. If one or more entropies are less than the entropy threshold, then the amplitude of one or more peaks is compared with the amplitude threshold. A fault signal is generated when one or more peak amplitudes are less than the amplitude threshold; and A baseline signal is generated when one or more entropies are less than an entropy threshold and one or more peak amplitudes are greater than an amplitude threshold.

[0100] Clause 19. The wind turbine power system according to Clauses 13 to 18, wherein determining at least one characteristic of one or more spectral components in the frequency band further includes: Calculate the location of one or more peak amplitudes of one or more spectral components within a frequency band; and Use one or more spectral components in the frequency band to monitor changes in friction. Among these factors, deteriorated lubrication leads to a gradual increase in friction and a change in the location of one or more peak amplitudes.

[0101] Clause 20. The wind turbine power system according to Clauses 13 to 19, wherein comparing at least one characteristic of one or more spectral components in the frequency band with at least one baseline value further includes: Generate a high-dimensional vector comprising multiple properties, wherein at least one property is included; and The high-dimensional vector is compared with a baseline cluster that includes similar vectors from the baseline generator.

[0102] This written description uses examples to disclose the present disclosure, including the best mode, and also enables any person skilled in the art to practice the present disclosure, including making and using any device or system and performing any incorporated methods. The patentability scope of this disclosure is defined by the claims and may include other examples that would occur to a person skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A method for preventing damage to bearings in a generator, the generator being electrically connected to a power conversion assembly having a first converter connected to a second converter, the method comprising: One or more electrical signals of the power conversion component are monitored via a controller; The controller converts the one or more electrical signals to the frequency domain; One or more spectral components in the frequency band of the frequency domain surrounding one or more known characteristic frequencies of the bearing are extracted via the controller; The controller determines the characteristics of the one or more spectral components in the frequency band, wherein determining the characteristics includes calculating one or more peak amplitudes of the one or more spectral components in the frequency band, and calculating one or more entropies of the one or more spectral components in the frequency band; The controller compares one or more entropies of one or more spectral components in the frequency band with an entropy threshold. When one or more entropies exceed the entropy threshold, a fault signal or baseline signal for the bearing is generated via the controller; If the one or more entropies are less than the entropy threshold, then the one or more peak amplitudes are compared with the amplitude threshold; The fault signal is generated when the amplitude of one or more peak values ​​is less than the amplitude threshold; and The baseline signal is generated when one or more entropies are less than the entropy threshold and one or more peak amplitudes are greater than the amplitude threshold; and In response to the generation of the fault signal, a control action is performed via the controller.

2. The method according to claim 1, wherein, The one or more electrical signals include at least one of current or voltage collected from the first converter.

3. The method according to claim 1, wherein, The generator is part of a wind turbine power system, the first converter is a rotor-side converter of the wind turbine power system, and the second converter is a line-side converter of the wind turbine power system, wherein the one or more electrical signals include at least one of current or voltage collected from the rotor-side converter or the line-side converter, and wherein the current includes a three-phase rotor current, and the voltage includes a three-phase rotor voltage of the rotor-side converter or the line-side converter.

4. The method according to claim 1, wherein, Converting the one or more electrical signals to the frequency domain further includes: Calculate the complex rotation vector of the one or more electrical signals; and Calculate the complex fast Fourier transform (FFT) of the complex rotation vector.

5. The method according to claim 1, wherein, A change in at least one of the one or more entropies or the one or more peak amplitudes indicates a deterioration in electrical discharge machining (EDM) damage in the bearing.

6. The method according to claim 1, wherein, Determining the characteristics of the one or more spectral components in the frequency band further includes: Calculate the location of the one or more peak amplitudes of the one or more spectral components in the frequency band; and The changes in friction are monitored using one or more spectral components in the frequency band. Deteriorated lubrication leads to a gradual increase in friction and a change in the location of the one or more peak amplitudes.

7. The method according to claim 1, further comprising: Generate a high-dimensional vector comprising multiple characteristics, wherein the multiple characteristics include the characteristics of the one or more spectral components; and The high-dimensional vector is compared with a cluster of baselines that includes similar vectors from the baseline generator.

8. The method according to claim 1, wherein, The control actions also include changing the operating setpoint of the generator or the power conversion component, shutting down the generator, generating an alarm, and arranging for the repair or replacement of at least one of at least one component of the generator.

9. A method for preventing damage to bearings in a generator of an electric power system, the electric power system having a power conversion assembly having a first converter coupled to a second converter, the power conversion assembly being electrically coupled to the generator, the method comprising: The controller monitors one or more electrical signals of the power conversion components of the power system, wherein the one or more electrical signals include at least one of current or voltage collected from the first converter or the second converter; The controller calculates the complex rotation vector of the one or more electrical signals; The complex fast Fourier transform (FFT) of the complex rotation vector is calculated via the controller; One or more spectral components in a frequency band surrounding one or more known characteristic frequencies of the bearing are extracted via the controller; The controller calculates one or more peak amplitudes in the frequency band; The controller calculates one or more entropies in the frequency band; The controller compares the one or more entropies with an entropy threshold. When one or more entropies exceed the entropy threshold, a fault signal for the bearing is generated via the controller; If the one or more entropies do not exceed the threshold, then the one or more peak amplitudes are compared with the amplitude threshold via the controller; When the amplitude of one or more peak values ​​is less than the amplitude threshold, the controller generates the fault signal for the bearing. When the one or more entropies are less than the entropy threshold and the one or more peak amplitudes are greater than the amplitude threshold, a baseline signal for the bearing is generated via the controller; and In response to the generation of the fault signal, a control action is performed via the controller.

10. A wind turbine power system connected to a power grid, the wind turbine power system comprising: A doubly fed induction generator (DFIG) includes a rotor, a stator, and at least one bearing; A power conversion assembly electrically connected to the DFIG, the power conversion assembly including a rotor-side converter connected to a line-side converter; A controller configured to control the wind turbine power system, the controller being configured to perform a plurality of operations, the plurality of operations including: Monitor one or more electrical signals of the power conversion component; Convert the one or more electrical signals to the frequency domain; Extract one or more spectral components from the frequency band of the frequency domain surrounding one or more known characteristic frequencies of the bearing; Determine the characteristics of the one or more spectral components in the frequency band, wherein determining the characteristics includes calculating one or more peak amplitudes of the one or more spectral components in the frequency band, and calculating one or more entropies of the one or more spectral components in the frequency band; The entropy of one or more spectral components in the frequency band is compared with an entropy threshold. When one or more entropies exceed the entropy threshold, a fault signal or baseline signal is generated for the bearing; If the one or more entropies are less than the entropy threshold, then the one or more peak amplitudes are compared with the amplitude threshold; The fault signal is generated when the amplitude of one or more peak values ​​is less than the amplitude threshold; and The baseline signal is generated when one or more entropies are less than the entropy threshold and one or more peak amplitudes are greater than the amplitude threshold; and In response to the generation of the fault signal, a control action is performed.

11. The wind turbine power system according to claim 10, wherein, The one or more electrical signals include at least one of current or voltage collected from the rotor-side converter or the line-side converter.

12. The wind turbine power system according to claim 10, wherein, Converting the one or more electrical signals to the frequency domain further includes: Calculate the complex rotation vector of the one or more electrical signals; and Calculate the complex fast Fourier transform (FFT) of the complex rotation vector.

13. The wind turbine power system according to claim 10, wherein, Determining the characteristics of the one or more spectral components in the frequency band further includes: Calculate the location of the one or more peak amplitudes of the one or more spectral components in the frequency band; and The changes in friction are monitored using one or more spectral components in the frequency band. Deteriorated lubrication leads to a gradual increase in friction and a change in the location of the one or more peak amplitudes.

14. The wind turbine power system according to claim 10, wherein, The plurality of operations also include: Generate a high-dimensional vector comprising multiple characteristics, wherein the multiple characteristics include the characteristics of the one or more spectral components; and The high-dimensional vector is compared with a cluster of baselines that includes similar vectors from the baseline generator.

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