System and method for detecting cable degradation of multiphase electrical machine

Abstract

A method to detect cable degradation of a multiphase electrical machine is disclosed. The method includes transmitting at least one electrical signal through the multiphase electrical machine. The method also includes receiving a plurality of signals through a plurality of cables connected to the multiphase electrical machine, the plurality of signals representative of the at least one electrical signal. The method also includes determining a difference between the plurality of signals. The method also includes comparing the difference with a pre-defined threshold to detect whether the connection has degraded at the plurality of cables, wherein the pre-defined threshold defines a value that represents a degraded connection of the plurality of cables with the multiphase electrical machine.

Description

700659-WO-1 / GECW-1262-PCTSYSTEM AND METHOD FOR DETECTING CABLE DEGRADATION OF MULTIPHASE ELECTRICAL MACHINEFIELD

[0001] The present disclosure relates generally to electrical machines, such as multiphase electrical machines, and more particularly, to systems and methods for detecting cable degradation of multiphase electrical machines.BACKGROUND

[0002] Wind power is considered one of the cleanest, most environmentally friendly energy' sources presently available, and wind turbines have gained increased attention in this regard. A modem wind turbine ty pically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. For example, rotor blades typically have the cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between the sides. Consequently, a lift force, which is directed from a pressure side towards a suction side, acts on the blade. The lift force generates torque on the main rotor shaft, which is typically geared to a generator for producing electricity.

[0003] Such generators may be included in the broader category of multiphase electrical machines. Multiphase electrical machines can include both generators and motors and typically include various connections, such as cables, so that the generator or motor may either output or receive power. However, these connections may degrade over time due to regular use, environmental factors, and / or destructive forces. Thus, to ensure that such machines continue operating at an acceptable level, an assessment of such connections is regularly scheduled.

[0004] However, assessing the connections of the multiphase electrical machines can be both time-consuming and labor-intensive. Moreover, such an assessment may not be cost-effective or may fail to diagnose an issue before it results in an undesirable outcome for the multiphase electrical machine. Thus, the industry is continually seeking new systems and methods for assessing the connections of multiphase electrical machines to determine if any degradation has occurred.700659-WO-1 / GECW-1262-PCT

[0005] In view of the foregoing, the present disclosure is directed to a system and method for detecting cable degradation of multiphase electrical machines. For example, the systems and methods of the present disclosure may be utilized to detect cable degradation without requiring the time, expense, and uncertainty of conventional means.BRIEF DESCRIPTION

[0006] Aspects and advantages of the present disclosure will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the present disclosure.

[0007] In one aspect, the present disclosure is directed to a method to detect cable degradation of a multiphase electrical machine. The method includes transmitting at least one electrical signal through the multiphase electrical machine. The method also includes receiving a plurality of signals through a plurality' of cables connected to the multiphase electrical machine where the plurality of signals represents the at least one electrical signal. The method also includes determining a difference between the plurality of signals. The method also includes comparing the difference with a predefined threshold to detect whether the connection has degraded at the plurality of cables where the pre-defined threshold defines a value that represents a degraded connection of the plurality of cables with the multiphase electrical machine.

[0008] In an embodiment, transmitting the at least one electrical signal includes transmitting the at least one electrical signal through a first cable connected to a first rotor winding of the multiphase electrical machine.

[0009] In another embodiment, the plurality of cables includes a second cable connected to a second rotor winding of the multiphase electrical machine and a third cable connected to a third rotor winding of the multiphase electrical machine.

[0010] In another embodiment, the first rotor winding includes a first phase of the multiphase electrical machine, the second rotor winding includes a second phase of the multiphase electrical machine, and the third rotor winding includes a third phase of the multiphase electrical machine.

[0011] In another embodiment, the first cable, the second cable, and the third cable each include a rotor cable.700659-WO-1 / GECW-1262-PCT

[0012] In another embodiment, the multiphase electrical machine includes a wind turbine power system where the first cable, the second cable, and the third cable each include at least one of an assembly cable connected to a converter, a tower cable connected to the wind turbine power system, a slip ring or a brush of the wind turbine power system, or a converter filter of the wind turbine power system.

[0013] In another embodiment, the method further includes closing a first switch of an electrical source so as to transmit the at least one electrical signal.

[0014] In another embodiment, the method further includes closing a plurality of electrical switches of the electrical source so as to receive the plurality of signals representative of the at least one electrical signal.

[0015] In another embodiment, the plurality of signals includes at least one of resistance, current, voltage, or functions thereof.

[0016] In another embodiment, the plurality of signals includes resistance, wherein the difference includes less than about 10 milliohms (m ).

[0017] In another embodiment, the pre-defined threshold includes a difference of at least 10% between the plurality of signals received through the plurality of cables.

[0018] In another embodiment, the method further includes determining the predefined threshold based on historical data indicative of a degraded connection of the plurality' of cables with the multiphase electrical machine.

[0019] In another embodiment, the method further includes determining the predefined threshold via at least one of machine learning.

[0020] In another embodiment, the method further includes determining the predefined threshold based on one or more environmental conditions.

[0021] In another embodiment, the one or more environmental conditions include at least one of temperature or humidity'.

[0022] In another embodiment, the method further includes autonomously transmitting the at least one electrical signal through the multiphase electrical machine and receiving the plurality of signals through the plurality of cables via a controller at a pre-determined time.

[0023] In another aspect, the present disclosure is directed to a system to detect cable degradation of a multiphase electrical machine. The system includes the multiphase electrical machine, an electrical source, a plurality of cables connected to700659-WO-1 / GECW-1262-PCT the multiphase electrical machine and the electrical source, and a controller communicatively coupled with the electrical source. In particular, the controller is configured to transmit, via the electrical source, at least one electrical signal through the multiphase electrical machine; receive, via the electrical source, a plurality of signals through the plurality of cables connected to the multiphase electrical machine, the plurality of signals representative of the at least one electrical signal; determine a difference between the plurality of signals; and compare the difference with a predefined threshold to detect whether the connection has degraded at the plurality of cables, wherein the pre-defined threshold defines a value that represents a degraded connection of the plurality of cables with the multiphase electrical machine.

[0024] These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] A full and enabling disclosure of the present disclosure, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

[0026] FIG. 1 illustrates a perspective view of an example embodiment of a wind turbine according to the present disclosure;

[0027] FIG. 2 illustrates a flow chart of an embodiment of a method to detect cable degradation of a multiphase electrical machine according to the present disclosure;

[0028] FIG. 3 illustrates a diagram of an example embodiment of a multiphase electrical machine according to the present disclosure;

[0029] FIG. 4 illustrates a resistance diagram of an embodiment of a multiphase electrical machine;

[0030] FIG. 5 illustrates a circuit diagram of an example embodiment of an electrical source including multiple switches to transmit and receive an electrical700659-WO-1 / GECW-1262-PCT signal to and from a multiphase electrical machine according to the present disclosure;

[0031] FIG. 6 illustrates a graph depicting a difference in cunent between electrical signals that have been received from different components connected with the multiphase electrical machine according to the present disclosure;

[0032] FIG. 7 illustrates various graphs depicting a difference in current between electrical signals that have been received from the multiphase electrical machine for positive and negative pulses according to the present disclosure; and

[0033] FIG. 8 illustrates various graphs depicting the derivative of total current observed for the electrical signals that have been received from the multiphase electrical machine according to the present disclosure.DETAILED DESCRIPTION

[0034] Reference now will be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of an explanation of the present disclosure, not a limitation of the present disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the present disclosure. For instance, features illustrated or described as part of an embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0035] As used herein, terms of approximation, such as “about,” “generally,” “approximately,” or “substantially,” include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, “generally vertical” includes directions within ten degrees of vertical in any direction, e.g., clockwise, or counterclockwise. Further, when a plurality of ranges is provided, any combination of a minimum value and a maximum value described in the plurality of ranges is contemplated by the present disclosure. For example, if ranges of “from about 20% to about 80%” and “from about 30% to about 70%” are described, a range of “from about 20% to about 70%” or a range of “from about 30%700659-WO-1 / GECW-1262-PCT to about 80%” are also contemplated by the present disclosure.

[0036] In general, the present disclosure is directed to systems and methods for detecting degradation of the cable for cables used with a multiphase electrical machine. Specifically, the degradation can be detected by transmitting an electrical signal through the multiphase electrical machine and receiving a plurality of signals representative of the electrical signal through a plurality of cables. The plurality of signals can then be used to detect the degradation of any of the plurality of cables. For example, a difference can be observed between signals of the plurality of signals and the difference can be compared with a pre-defined threshold that is representative of a degradation of the cable connection.

[0037] Thus, in certain embodiments, the systems and methods are capable of being implemented to detect a degradation of the cables or the cable connection in relation to a multiphase electrical machine. Thus, the time, cost, and uncertainty associated may be reduced. For example, in an embodiment, the present systems and methods may reduce the requirement of on-site technicians to check the cable connections. In addition, by determining the quality’ of the cable connection based on a threshold, the certainty and reliability may be increased.

[0038] Moreover, in an embodiment, the systems and methods may be able to be implemented autonomously so the time and expense of doing diagnostic checks on the cables may be further reduced. Further, in an embodiment, the pre-defined thresholds may be defined using machine learning, historical data, or environmental factors for the multiphase electrical machine so the certainty of the diagnostic checks may be further improved.

[0039] Referring now to the drawings. FIG. 1 illustrates a perspective view of one embodiment of a wind turbine 10 that may implement the diagnostic technology according to the present disclosure. As described, the wind turbine 10 is one example of a multiphase electrical machine that the systems and methods can be implemented with. Other examples are not limited to but may include multiphase generators, multiphase electrical motors, multiphase electrical storage devices, or any other similar machine. More particularly, the systems and methods may also be utilized with a doubly fed induction generator (DFIG) or any other type of multiphase electrical machine such as a variable frequency driven (VFD) machine or a converter-700659-WO-1 / GECW-1262-PCT fed machine.

[0040] As shown, the wind turbine 10 generally includes a tower 12 extending from a support surface 14. 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 outwardly from the hub 20. For example, in the illustrated embodiment, the rotor 18 includes three rotor blades 22. However, in an alternative embodiment, the rotor 18 may include more or less than three rotor blades 22. Each rotor blade 22 may be spaced about the hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the hub 20 may be rotatably coupled to an electric generator 24 positioned within the nacelle 16 to permit electrical energy to be produced.

[0041] The wind turbine 10 may also include a wind turbine controller 26 centralized within the nacelle 16. However, in other embodiments, the controller 26 may be located within any other component of the wind turbine 10 or at a location outside the wind turbine. Further, the controller 26 may be communicatively coupled to any number of the components internal to or external to the wind turbine 10 in order to control the operation of such components and / or to implement a correction action. As such, the controller 26 may include a computer or other suitable processing unit. Thus, in several embodiments, the controller 26 may include suitable computer-readable instructions that, when implemented, configure the controller 26 to perform various functions, such as receiving, transmitting, and / or executing wind turbine control signals. Accordingly, the controller 26 may generally be configured to control the various operating modes (e.g., start-up or shut-down sequences), de-rate the wind turbine, and / or control various components of the wind turbine 10 as will be discussed in more detail below. As will be discussed in greater detail below, the controller 26 may also be communicatively coupled (such as either with a direct connection, a wired connection, or a wireless connection) with an electrical source, such as generator 24 or a converter, and implemented to diagnose an electrical connection of cables associated with the wind turbine 10. As described, the term “connection” may refer to, but is not to be construed as limited to, the electrical signal passing through the cables, the mechanical or electrical state of the cables, or the700659-WO-1 / GECW-1262-PCT mechanical or electrical connection between the cables.

[0042] Referring now to FIG. 2, a flow chart of an embodiment of a method to detect cable connection degradation of a multiphase electrical machine according to the present disclosure. The method 100 may be implemented with the wind turbine 10 and components of the wind turbine 10. Method 100 may also be implemented with components that will be described herein as an alternative or in addition to the components of the wind turbine 10.

[0043] As shown at (102), the method 100 includes transmitting at least one electrical signal through a multiphase electrical machine, such as the wind turbine 10 or any other multiphase electrical machine described hereinabove. For example, referring now to FIGS. 3-5, the electrical signal(s) can be transmitted from a converter 204 to a multiphase electrical machine 202. Specifically, the electrical signal(s) can be transmitted from the converter 204, via converter connections 216a, 216b, 216c, through any one of the cables 210a, 210b, 210c that are exterior and connected to the multiphase electrical machine 202 (see FIG. 4). The exterior cables 210a, 210b, 210c can include any variety of cables configured to transmit the electrical signal(s). For example, if the multiphase electrical machine 202 is a wind turbine power system used with the wind turbine 10, the exterior cables 210a, 210b, 210c could be assembly cables 218a, 218b, 218c, tower cables 220a, 220b. 220c, or drip loop cables 222a, 222b. 222c (see FIG. 4).

[0044] From the exterior cables 210a, 210b, 210c, the electrical signal(s) can be transmitted to a corresponding contact of the multiphase electrical machine 202 such as corresponding slip rings 212a, 212b, 212c, and brushes 214a, 214b, 214c (see FIG. 4). If a converter filter is utilized with the converter 204, such as through the use of capacitors 244. 246, 248 and resistor 250 (see FIG. 5), the electrical signal(s) may also be transmitted through the converter filter of the converter 204.

[0045] From the corresponding contact, the electrical signal(s) can be transmitted to a corresponding rotor winding 208a, 208b, 210c via connected corresponding rotor cables 206a, 206b, 206c. However, the present systems and methods may also be capable of accounting for different configurations of rotors and stators such that the electrical signal is transmitted to stator windings (not shown).

[0046] As an example of a full transmission, an electrical signal can be700659-WO-1 / GECW-1262-PCT transmitted from the converter 204 via converter contact 216a through the exterior cable 210a to the slip ring 212a and brush 214a to the rotor cable 206a to the rotor w inding 208a. As described, each of the rotor windings 208a, 208b, 208c defines a phase of the multiphase electrical machine 202 that is distinct from the other.

[0047] To initiate this transmission, the electrical signal(s) can be transmitted by closing corresponding switches 228, 230, 232. 234, 236, 238 contained within the converter 204 such that current travels from a first terminal 240 through the multiphase electrical machine 202 to a second terminal 242. For example, to transmit an electrical signal to a first rotor winding, such as rotor winding 206a, switch 228 may be closed. In another example, an electrical signal may be transmitted to rotor winding 208b by closing switch 230 and an electrical signal can be transmitted to rotor winding 208c by closing switch 232.

[0048] As described, the electrical signal may be a positive or negative pulse or multiple pulses of current passing from the converter 204 to the multiphase electrical machine 202. If a positive pulse is utilized, then switch 228, switch 230, or switch 232 may be closed. However, if a negative pulse is utilized, then switch 234. switch 236, or switch 238 may be closed. A positive pulse may travel from the first terminal 240 to the second terminal 242, while a negative pulse may travel from the second terminal 242 to the first terminal 240. A positive pulse may result in a positive voltage or current reading, while a negative pulse may result in a negative voltage or current reading from sensors 252a, 252b, 252c as will be described in greater detail hereinbelow. Further, both positive and negative pulses may be beneficial in analyzing the components connected between the converter 204 and the multiphase electrical machine 202 as will be described in greater detail hereinbelow. The positive or negative pulse(s) time may range from about 1 millisecond (ms) to 40 ms, such as about 10 ms to 30 ms, such as about 15 ms to 20 ms.

[0049] In addition, the transmission of the electrical signal(s) may be implemented autonomously. Specifically, a controller, such as controller 26, may contain instructions to send an electrical signal at a pre-determined time such as yearly, bi-yearly, or quarterly. The electrical signal may also be sent autonomously in response to conditions such as a fault occurring within the multiphase electrical machine 202 or in response to a period of elevated environmental conditions such as a700659-WO-1 / GECW-1262-PCT period of high wind speeds.

[0050] As shown at (104), the method 100 includes receiving a plurality of signals through a plurality of cables connected to the multiphase electrical machine, the plurality of signals representative of the at least one electrical signal. For example, if the electrical signal(s) is / are transmitted to rotor winding 208a, a signal or signals may be received by the converter 204 from second and third rotor winding, such as rotor windings 208b and 208c via rotor cables 206b, 206c. In particular, electrical signal(s) sent to rotor winding 208a may pass through the multiphase electrical machine 202 and exit as at least two signals respectively via rotor windings 208b, 208c. Further, as shown, the at least tw o or a plurality of signals may travel in parallel to each other. More particularly, the travel path of the plurality’ of signals may include rotor cables 206b, 206c, slip rings 212b, 212c and brushes 214b, 214c, exterior cables 210b, 210c, and converter connections 216b, 216 before arriving back at the converter 204. However, it should be understood that the electrical signal(s) may be transmitted to either rotor winding 208b or rotor winding 208c, and the plurality of signals may also originate from rotor winding 208a. Thus, it can be understood that the plurality’ of signals originate from the electrical signal(s) and are representative of the electrical signal(s).

[0051] Similar to the initiation of the transmission, the receiving of the plurality of signals may be accomplished by closing corresponding switches 228, 230. 232, 234, 236, 238 contained within the converter 204 such that current travels from a first terminal 240 through the multiphase electrical machine 202 to the second terminal 242. For example, to receive the signal(s) that is / are traveling from rotor winding 208b. switch 236 may be closed, and to receive the signal(s) that is / are traveling from rotor winding 208c, switch 238 may be closed. Alternatively, if rotor winding 208a is receiving a signal or signals, switch 234 may be closed. Thus, it can be seen that through the operation of syvitches 228, 230, 232, 234, 236, 238 contained yvithin the converter 204, electrical signals may be transmitted and received to and from rotor windings 208a. 208b, 208c.

[0052] As described hereinabove, the electrical signal may be a positive or negative pulse or multiple pulses of current passing from the converter 204 to the multiphase electrical machine 202. For receiving the signal, which is representative700659-WO-1 / GECW-1262-PCT of the electrical signal, corresponding switches may be closed to receive signals representative of positive or negative pulses. For example, if a positive pulse is transmitted, then switch 234. switch 236, or switch 238 may be closed to receive the positive pulse. In an example of a positive pulse, switch 228 is closed and for the receiving pulse of the pulse, both switches 236 and 238 are closed. However, if a negative pulse is transmitted, then switch 228, switch 230, or switch 232 may be closed to receive the negative pulse. Thus, as stated above, a positive pulse may travel from the first terminal 240 and be received by the second terminal 242, while a negative pulse may travel from the second terminal 242 and be received by the first terminal 240.

[0053] As shown at (106), the method 100 includes determining a difference between the plurality of signals. For example, sensors 252a, 252b, 252c may be placed on the transmission and receiving path of the electrical signal(s) and the plurality of signals. Specifically, if the electrical signal is transmitted to rotor winding 208a, the parameters of the electrical signal may be observed by sensor 252a. Then, when the plurality of signals are received, the parameters of the signal(s) traveling from rotor winding 208b may be observed by sensor 252b, and the parameters of the signal(s) traveling from rotor winding 208c may be observed by sensor 252c.

[0054] Although depicted as directly adjacent to the converter 204, it should be understood that the sensors 252a, 252b, 252c may be placed at any location of the connection between the converter 204 and the multiphase electrical machine 202. Further, it should be understood that the sensors 252a, 252b, 252c may be capable of determining the parameters at any location on each respective branch between the converter 204 and the multiphase electrical machine 202. That is, generally the sensors 252a. 252b, 252c may be capable of detecting the parameters of any of the components within the turbine such as the resistances 226a, 226b, 226c or inductances 224a, 224b, 224c at the rotor windings 208a, 208b, 208c or the resistances or inductances of any of the other components between the rotor windings 208a, 208b, 208c and the converter. In another example, as shown, the sensor 252b may be capable of determining the parameters of the signal at the rotor cable 206b, and the sensor 252c may be capable of determining the parameters of the signal at the rotor cable 206c.700659-WO-1 / GECW-1262-PCT

[0055] As described, the parameters may include but are not limited to, at least one of resistance, current, voltage, or functions thereof. For example, sensors 252b, 252c may be utilized to determine the resistance observed at the rotor cables 206b. 206c respectively. Further, the differences can be observed by sensors 252b, 252c between the resistances at the rotor cables 206b, 206c respectively. These resistances may be observed by measuring the current or voltage at the rotor cables 206b, 206c. For example, referring now to FIG. 6, a graph depicting a difference in current between electrical signals that have been received from different components connected with the multiphase electrical machine is illustrated. FIG. 6 may be better understood with reference to Table 1 provided hereinbelow.

[0056] As shown in graph 300, the current measured at rotor cable 206b compared with current measured at rotor cable 206c is shown for vary ing conditions. However, it should be noted that current could also be measured at rotor cable 206a or any other components connected with the multiphase electrical machine 202. As shown, line 302 depicts the resistance at a baseline level for all of the rotor cables 206a, 206b, 206c. In this scenario, no difference in current is depicted between rotor cables 206b, 206c, as shown in FIG. 6, because no difference in resistance is observed between rotor cables 206b, 206c.

[0057] As shown, line 304 depicts the current for default conditions, such as those observed with the circuit diagram depicted in FIG. 4, with the connection of the rotor cables 206a, 206b, 206c. Specifically, with reference to FIG. 4, rotor cables 206b, 206c have a default lower resistance than rotor cable 206a given that rotor cables 206b, 206c are connected in parallel with each other unlike rotor cable 206a. However, because the resistance at rotor cables 206b, 206c is the same, no difference is depicted in the current at line 304.

[0058] At line 306. the current and the resistance for rotor cables 206b. 206c are700659-WO-1 / GECW-1262-PCT different. In this scenario, as shown in line 306, the difference in current between rotor cables 206b, 206c can be readily observed indicating that the resistance is different. Accordingly, by measuring the current passing through the rotor cables 206b, 206c, the resistance of the rotor cables 206b, 206c can be observed.

[0059] Specifically, with regard to resistance, a difference of less than about 10 milliohms (mQ) may be observed, such as between about 10 and 0.1 mQ, such as between about 5 and 0.3 m . such as between about 2 and 0.5 mQ. Thus, through the use of sensors 252a, 252b, 252c the parameters of the electric signal and plurality of signals may be determined and differences between these parameters may be derived.

[0060] Differences may be further determined through the use of positive and negative pulses as described hereinabove. For example, now referring to FIG. 7, various graphs depicting a difference in cunent between electrical signals that have been received from the multiphase electrical machine for positive and negative pulses are illustrated.

[0061] As shown at graph 400 and graph 450, positive and negative pulses may be sent as described above and the currents between components may be compared.Further, the current measured at rotor cables 206a, 206b, 206c due to the positive or negative pulses may be compared. The current compared at rotor cables 206a, 206b, 206c may be understood with reference to the configuration shown and described in FIGS. 3-5. Specifically, each of the comparisons that are provided in graphs 400, 450 depict the rotor cables 206a, 206b, 206c being compared as they receive the signal from the multiphase electrical machine. For example, when the rotor cable 206a and rotor cable 206b are compared, rotor cables 206a, 206b are connected in parallel at the locations depicted as rotor cables 206b, 206c as shown in FIG. 4. In another example, when the rotor cable 206a and rotor cable 206c are compared, rotor cables 206a, 206c are connected in parallel at the locations depicted as rotor cables 206b, 206c as show n in FIG. 4.

[0062] Now referring to graph 400, the current measured at rotor cables 206a, 206b. 206c is shown as being compared as a result of a positive pulse. In particular, line 404 depicts the difference in current between rotor cable 206b and 206c due to a first positive pulse. Line 402 depicts the difference in current between rotor cable 206b and 206c after a third positive pulse. Line 408 depicts the difference in current700659-WO-1 / GECW-1262-PCT between rotor cable 206a and 206c due to a first positive pulse. Line 406 depicts the difference in cunent between rotor cable 206a and 206c after a third positive pulse. Line 412 depicts the difference in current between rotor cable 206a and 206b due to a first positive pulse. Line 410 depicts the difference in current between rotor cable 206a and 206b after a third positive pulse. As shown at lines 402-412, a difference in current is observed between each configuration of the rotor cables 206a, 206b, 206c by utilizing a positive pulse as indicated by the lines 402-412 not being minimized. Thus, it can be understood that there is a difference in resistance in the rotor cables 206a, 206b, 206c as compared with each other.

[0063] Further, when comparing the lines 404, 408, 412 to lines 402, 406, 410, it can be seen that multiple positive pulses, such as at least three positive pulses, may provide further indication that a difference in current, and consequently, a difference in resistance, is present betw een the rotor cables 206a, 206b, 206c. For example, it can be seen that line 412 is less than line 410 indicating that the third positive pulse indicated that there was a difference in current and resistance between rotor cables 206a. 206b that a first positive pulse initially did not determine.

[0064] Now referring to graph 450, the current measured at rotor cables 206a, 206b, 206c is shown as being compared as a result of a negative pulse. In particular, line 454 depicts the difference in current between rotor cable 206b and 206c due to a first negative pulse. Line 452 depicts the difference in current between rotor cable 206b and 206c after a third negative pulse. Line 458 depicts the difference in current between rotor cable 206a and 206c due to a first negative pulse. Line 456 depicts the difference in current between rotor cable 206a and 206c after a third negative pulse. Line 462 depicts the difference in current between rotor cable 206a and 206b due to a first negative pulse. Line 460 depicts the difference in current between rotor cable 206a and 206b after a third negative pulse. As shown at lines 452-462, a difference in current is observed betw een each configuration of the rotor cables 206a, 206b, 206c by utilizing a negative pulse as indicated by the lines 452-462 not being minimized.

[0065] Further, when comparing graph 400 with graph 450 it can be seen that the negative pulse can indicate differences in current and resistance that the positive pulse may not, and vice versa. For example, comparing line 404 with line 454 it can be seen that the difference in current betw een rotor cables 206b, 206c is greater for the700659-WO-1 / GECW-1262-PCT negative pulse than the positive pulse. Thus, it can be seen that further utilization of positive and negative pulses may provide further information as it relates to the resistances and current found within components such as the rotor cables 206a. 206b, 206c.

[0066] Further still, when comparing the lines 454, 458, 462 to lines 452, 456, 460, it can be seen that multiple negative pulses, such as at least three negative pulses, may provide further indication that a difference in current, and consequently, a difference in resistance, is present between the rotor cables 206a, 206b, 206c. For example, it can be seen that line 462 is less than line 460 indicating that the third negative pulse indicated that there was a difference in current and resistance between rotor cables 206a, 206b that a first negative pulse initially did not determine.

[0067] Differences between resistance and current of components may also be determined by looking at the current observed within the components, or more specifically, a derivative of the current. For example, now referring to FIG. 8, various graphs depicting the derivative of current between electrical signals that have been received from the multiphase electrical machine for positive and negative pulses are illustrated. As shown at graphs 500, 530, 560, the derivative of the current may be measured for a variety of configurations similar to the configurations described above with reference to graphs 400, 450. Specifically, graph 500 depicts the derivative of the current observed at the rotor cables 206a, 206b, 206c when rotor cable 206a is the transmitting component and rotor cables 206b, 206c are the receiving components. More specifically, line 502 depicts the derivative of the current passing through rotor cable 206a, line 504 depicts the derivative of the current passing through rotor cable 206b. and line 506 depicts the derivative of the current passing through rotor cable 206c. when rotor cable 206a is the transmitting component and rotor cables 206b, 206c are the receiving components.

[0068] Graph 530 depicts the derivative of the current observed at the rotor cables 206a, 206b, 206c when rotor cable 206b is the transmitting component and rotor cables 206a, 206c are the receiving components. In particular, line 532 depicts the derivative of the current passing through rotor cable 206a, line 534 depicts the derivative of the current passing through rotor cable 206b, and line 536 depicts the derivative of the current passing through rotor cable 206c, when rotor cable 206b is700659-WO-1 / GECW-1262-PCT the transmitting component and rotor cables 206a, 206c are the receiving components.

[0069] Graph 560 depicts the derivative of the current observed at the rotor cables 206a. 206b, 206c when rotor cable 206c is the transmitting component and rotor cables 206a, 206b are the receiving components. Specifically, line 562 depicts the derivative of the current passing through rotor cable 206a, line 564 depicts the derivative of the current passing through rotor cable 206b, and line 566 depicts the derivative of the current passing through rotor cable 206c, when rotor cable 206c is the transmitting component and rotor cables 206a, 206b are the receiving components.

[0070] Thus, when viewing graphs 500, 530, 560, it can be seen that differences between the derivatives of current may be observed for a variety of configurations. For example, when viewing graph 500, a difference between line 504 and line 506 may indicate that there is a difference between the derivative of current for rotor cable 206b and rotor cable 206c when they are the receiving components, for example, shown in FIG. 4. Further, when viewing graph 530, a difference betw een line 532 and line 536 may indicate that there is a difference between the derivative of current for rotor cable 206a and rotor cable 206c when they are the receiving components. However, when viewing graph 560, a lack of difference between line 562 and line 564 may indicate that there is no difference between the derivative of current for rotor cable 206a and rotor cable 206b when they are the receiving components. Like FIG. 7, multiple pulses may also be utilized when observing the derivative of the current passing through the components.

[0071] Referring back to FIG. 2, as shown at (108), the method 100 includes comparing the difference with a pre-defined threshold to detect whether the connection has degraded at the plurality of cables where the pre-defined threshold defines a value that represents a degraded connection of the plurality of cables with the multiphase electrical machine. For example, the pre-defined threshold may relate to or be any of the values of the observed differences described above with reference to FIGS. 6-8. Further, the pre-defined threshold may be greater or less than the differences described above with reference to FIGS. 6-8. In addition, the pre-defined threshold may be defined by a percentage difference of resistance, current, voltage, or functions thereof. For example, the pre-defined threshold may define a difference of at least about 5%, at least about 7.5%, or at least about 10% between the plurality of700659-WO-1 / GECW-1262-PCT signals received through the plurality' of cable, such as rotor cables 206a, 206b, 206c. Such a percentage may indicate that the cables have degraded such that maintenance is warranted.

[0072] The pre-defined threshold may also be defined by utilizing historical data indicative of a degraded connection for the particular component, such as the rotor cables 206a, 206b, 206c, or the particular multiphase electrical machine being utilized. For example, the pre-defined threshold may initially be set at least about 10% for the particular component or multiphase electrical machine. However, if it is later observed that a degraded connection exists at a pre-defined threshold of at least about 5%, the pre-defined threshold may be updated to be at least about 5% for future assessments of that particular component or that particular multiphase electrical machine. Alternatively, the pre-defined threshold may also be raised, such as from at least about 5% to at least about 10%, if it is determined that the connection has not degraded for that particular component or that particular multiphase electrical machine when measured at the lower threshold (i.e.. at least about 5%).

[0073] In addition, the pre-defined threshold may also be determined using machine learning. For example, a trend of increases and decreases, as described above, may be input into a machine learning algorithm which may be utilized to determine an updated pre-defined threshold for a particular component or multiphase electrical machine. Further, the machine learning algorithm may forgo the need for user input to determine updated pre-defined thresholds.

[0074] Further, an algorithm may also be utilized to determine a pre-defined threshold in a scenario when comparing cables that have dissimilar sizes. For example, if one of the cables is thinner, then the algorithm may account for an increase in resistance or an increase in current.

[0075] Additionally, environmental conditions may also be utilized to either determine pre-defined thresholds or modify the pre-defined thresholds that are determined. The environmental conditions may include at least one of temperature or humidity. For example, if a pre-defined threshold of at least about 5% is indicative of a degraded component at a set temperature, then a pre-defined threshold of at least about 10% may be utilized at an elevated temperature to account for the temperature impact on the components. Similarly, if a pre-defined threshold of at least about 10%700659-WO-1 / GECW-1262-PCT is indicative of a degraded component at a set humidity, then a pre-defined threshold of at least about 5% may be utilized at a higher humidity level to account for the impact of humidity on the components.

[0076] Thus, as described hereinabove, through the use of the systems and methods, a degraded connection of a multiphase electrical machine may be detected for a variety' of components using a variety' of means and variables.

[0077] Various aspects and embodiments of the present invention are defined by the following numbered clauses:Clause 1. A method to detect cable degradation of a multiphase electrical machine, the method comprising: transmitting at least one electrical signal through the multiphase electrical machine; receiving a plurality of signals through a plurality of cables connected to the multiphase electrical machine, the plurality7of signals representative of the at least one electrical signal; determining a difference between the plurality of signals; and comparing the difference with a pre-defined threshold to detect whether the connection has degraded at the plurality of cables, wherein the pre-defined threshold defines a value that represents a degraded connection of the plurality of cables with the multiphase electrical machine.Clause 2. The method of clause 1 , wherein transmitting the at least one electrical signal comprises transmitting the at least one electrical signal through a first cable connected to a first rotor winding of the multiphase electrical machine.Clause 3. The method of clause 2, wherein the plurality' of cables comprises a second cable connected to a second rotor winding of the multiphase electrical machine and a third cable connected to a third rotor winding of the multiphase electrical machine.Clause 4. The method of clause 3, wherein the first rotor winding comprises a first phase of the multiphase electrical machine, the second rotor winding comprises a second phase of the multiphase electrical machine, and the third rotor winding comprises a third phase of the multiphase electrical machine.700659-WO-1 / GECW-1262-PCTClause 5. The method of any of clauses 3-4, wherein the first cable, the second cable, and the third cable each comprise a rotor cable.Clause 6. The method of any of clauses 3-5, wherein the multiphase electrical machine comprises a wind turbine power system, wherein the first cable, the second cable, and the third cable each comprise at least one of an assembly cable connected to a converter, a tower cable connected to the wind turbine power system, a slip ring or a brush of the wind turbine power system, or a converter filter of the wind turbine power system.Clause 7. The method of any of the preceding clauses, further comprising closing a first switch of an electrical source so as to transmit the at least one electrical signal.Clause 8. The method of clause 7, further comprising closing a plurality of electrical switches of the electrical source so as to receive the plurality of signals representative of the at least one electrical signal.Clause 9. The method of any of the preceding clauses, wherein the plurality of signals comprises at least one of resistance, current, voltage, or functions thereof.Clause 10. The method of clause 9, wherein the plurality of signals comprise resistance, wherein the difference comprises less than about 10 milliohms (mQ).Clause 11. The method of any of the preceding clauses, wherein the predefined threshold comprises a difference of at least 10% between the plurality of signals received through the plurality of cables.Clause 12. The method of any of the preceding clauses, further comprising determining the pre-defined threshold based on historical data indicative of a degraded connection of the plurality of cables with the multiphase electrical machine.Clause 13. The method of any of the preceding clauses, further comprising determining the pre-defined threshold via at least one of machine learning.Clause 14. The method of any of the preceding clauses, further comprising determining the pre-defined threshold based on one or more environmental conditions.Clause 15. The method of clause 14, wherein the one or more700659-WO-1 / GECW-1262-PCT environmental conditions comprises at least one of temperature or humidity.Clause 16. The method of any of the preceding clauses, further comprising autonomously transmitting the at least one electrical signal through the multiphase electrical machine and receiving the plurality of signals through the plurality of cables via a controller at a pre-determined time.Clause 17. A sy stem to detect cable degradation of a multiphase electrical machine, the system comprising: the multiphase electrical machine; an electrical source; a plurality of cables connected to the multiphase electrical machine and the electrical source; and a controller communicatively coupled with the electrical source, the controller configured to: transmit, via the electrical source, at least one electrical signal through the multiphase electrical machine; receive, via the electrical source, a plurality of signals through the plurality of cables connected to the multiphase electrical machine, the plurality of signals representative of the at least one electrical signal; determine a difference between the plurality of signals; and compare the difference with a pre-defined threshold to detect whether the connection has degraded at the plurality of cables, wherein the pre-defined threshold defines a value that represents a degraded connection of the plurality of cables with the multiphase electrical machine.Clause 18. The system of clause 17, wherein transmitting at least one electrical signal comprises closing a first switch of the electrical source so as to transmit the at least one electrical signal.Clause 19. The system of clause 18, wherein receiving the plurality of signals through the plurality of cables comprises closing a plurality of electrical switches of the electrical source so as to receive the plurality of signals representative of the at least one electrical signal.Clause 20. The system of any of clauses 17-19, wherein the multiphase electrical machine comprises a wind turbine power system, wherein the plurality of700659-WO-1 / GECW-1262-PCT cables comprise at least one of an assembly cable connected to a converter, a tower cable connected to the wind turbine power system, a slip ring or a brush of the wind turbine power system, or a converter filter of the wind turbine power system.

[0078] This written description uses examples to disclose the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the present disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the present disclosure is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

700659-WO-1 / GECW-1262-PCTWHAT IS CLAIMED IS:

1. A method to detect cable degradation of a multiphase electrical machine, the method comprising: transmitting at least one electrical signal through the multiphase electrical machine; receiving a plurality of signals through a plurality of cables connected to the multiphase electrical machine, the plurality of signals representative of the at least one electrical signal; determining a difference between the plurality7of signals; and comparing the difference with a pre-defmed threshold to detect whether the connection has degraded at the plurality of cables, wherein the pre-defmed threshold defines a value that represents a degraded connection of the plurality of cables with the multiphase electrical machine.

2. The method of claim 1 , wherein transmitting the at least one electrical signal comprises transmitting the at least one electrical signal through a first cable connected to a first rotor winding of the multiphase electrical machine.

3. The method of claim 2, wherein the plurality of cables comprises a second cable connected to a second rotor winding of the multiphase electrical machine and a third cable connected to a third rotor winding of the multiphase electrical machine.

4. The method of claim 3. wherein the first rotor winding comprises a first phase of the multiphase electrical machine, the second rotor winding comprises a second phase of the multiphase electrical machine, and the third rotor winding comprises a third phase of the multiphase electrical machine.

5. The method of claim 3. wherein the first cable, the second cable, and the third cable each comprise a rotor cable.

6. The method of claim 3, wherein the multiphase electrical machine700659-WO-1 / GECW-1262-PCT comprises a wind turbine power system, wherein the first cable, the second cable, and the third cable each comprise at least one of an assembly cable connected to a converter, a tower cable connected to the wind turbine power system, a slip ring or a brush of the wind turbine power system, or a converter filter of the wind turbine power system.

7. The method of claim 1. further comprising closing a first switch of an electrical source so as to transmit the at least one electrical signal.

8. The method of claim 7, further comprising closing a plurality7of electrical switches of the electrical source so as to receive the plurality of signals representative of the at least one electrical signal.

9. The method of claim 1, wherein the plurality of signals comprises at least one of resistance, current, voltage, or functions thereof.

10. The method of claim 9, wherein the plurality of signals comprise resistance, wherein the difference comprises less than about 10 milliohms (mfi).

11. The method of claim 1. wherein the pre-defined threshold comprises a difference of at least 10% between the plurality of signals received through the plurality of cables.

12. The method of claim 1. further comprising determining the pre-defined threshold based on historical data indicative of a degraded connection of the plurality of cables with the multiphase electrical machine.

13. The method of claim 1, further comprising determining the pre-defined threshold via at least one of machine learning.

14. The method of claim 1, further comprising determining the pre-defined threshold based on one or more environmental conditions.700659-WO-1 / GECW-1262-PCT15. The method of claim 14, wherein the one or more environmental conditions comprises at least one of temperature or humidity.

16. The method of claim 1, further comprising autonomously transmitting the at least one electrical signal through the multiphase electrical machine and receiving the plurality of signals through the plurality of cables via a controller at a pre-determined time.

17. A system to detect cable degradation of a multiphase electrical machine, the system comprising: the multiphase electrical machine; an electrical source; a plurality of cables connected to the multiphase electrical machine and the electrical source; and a controller communicatively coupled with the electrical source, the controller configured to: transmit, via the electrical source, at least one electrical signal through the multiphase electrical machine; receive, via the electrical source, a plurality of signals through the plurality of cables connected to the multiphase electrical machine, the plurality of signals representative of the at least one electrical signal; determine a difference between the plurality of signals; and compare the difference with a pre-defined threshold to detect whether the connection has degraded at the plurality of cables, wherein the pre-defined threshold defines a value that represents a degraded connection of the plurality of cables with the multiphase electrical machine.

18. The system of claim 17, wherein transmitting at least one electrical signal comprises closing a first switch of the electrical source so as to transmit the at least one electrical signal.700659-WO-1 / GECW-1262-PCT19. The system of claim 18, wherein receiving the plurality7of signals through the plurality of cables comprises closing a plurality of electrical switches of the electrical source so as to receive the plurality of signals representative of the at least one electrical signal.

20. The system of claim 17, wherein the multiphase electrical machine comprises a wind turbine power system, wherein the plurality of cables comprise at least one of an assembly cable connected to a converter, a tower cable connected to the wind turbine power system, a slip ring or a brush of the w ind turbine power system, or a converter filter of the wind turbine power system.

Images