WO2022040139A1

WO2022040139A1 - Generator inspection tool

Info

Publication number: WO2022040139A1
Application number: PCT/US2021/046235
Authority: WO
Inventors: Benjamin STUTZ; Mark W. Fischer; Lukas DEMSEY; Carl R. LARSON; Keith Powell
Original assignee: Siemens Energy Inc
Current assignee: Siemens Energy Inc
Priority date: 2020-08-21
Filing date: 2021-08-17
Publication date: 2022-02-24
Anticipated expiration: 2023-02-21

Abstract

An inspection tool for inspecting a stator of a generator with a rotor positioned within the stator includes a carriage sized to fit within a gap between the rotor and the stator, a drive assembly coupled to the carriage, the drive assembly including drive motor operable to move the carriage along the stator in an axial direction, and a motor control operable using pulse width modulation to operate the drive motor. In addition, the inspection tool further includes a sensor operable to sense a feature of the stator, and a distance measuring device coupled to the carriage and operable to measure the position of the carriage with respect to the stator.

Description

GENERATOR INSPECTION TOOL

BACKGROUND

[0001] Electrical generators such as those used in large-scale power generation include a rotor that is supported for rotation within a stator. The rotor and the stator cooperate to define an annular airgap therebetween, to reduce disassembly, it is desirable to inspect the stator and/or the rotor without removing the rotor from the stator.

BRIEF SUMMARY

[0002] In one construction, an inspection tool for inspecting a stator of a generator with a rotor positioned within the stator includes a carriage sized to fit within a gap between the rotor and the stator, a drive assembly coupled to the carriage, the drive assembly including drive motor operable to move the carriage along the stator in an axial direction, and a motor control operable using pulse width modulation to operate the drive motor. In addition, the inspection tool further includes a sensor operable to sense a feature of the stator, and a distance measuring device coupled to the carriage and operable to measure the position of the carriage with respect to the stator.

[0003] In another construction, an inspection tool for inspecting a stator of a generator with a rotor positioned within the stator includes a carriage sized to fit within a gap between the rotor and the stator, a first drive member coupled to the carriage and operable to move the carriage in the axial direction, and a first drive motor coupled to the drive member. In addition, a first motor control operable using pulse width modulation to drive the first drive motor, a chattock coil coupled to the carriage, the chattock coil including a signal conditioner mounted to the carriage, a camera coupled to the carriage and movable to image a desired location, a laser coupled to the carriage and operable to measure the position of the carriage with respect to the stator, a control cable, and a cable clamp arranged to couple the control cable to the carriage. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0005] FIG. 1 is a perspective partially sectioned view of a generator including a stator and a rotor.

[0006] FIG. 2 is an end view of the rotor and stator of FIG. 1.

[0007] FIG. 3 is an end view of the rotor and stator of FIG. 1 and further including a generator inspection tool.

[0008] FIG. 4 is a perspective view of the generator inspection tool of FIG. 3.

[0009] FIG. 5 is another perspective view of the generator inspection tool of FIG. 3.

[0010] FIG. 6 is a perspective view of the front portion of the generator inspection tool of FIG. 3 including a camera mount.

[0011] FIG. 7 is a perspective view of the camera mount of FIG. 6.

[0012] FIG. 8 is a perspective view of a tail portion of the generator inspection tool of FIG. 3 including a cable clamp.

[0013] FIG. 9 is a partial exploded view of the cable clamp of FIG. 8.

[0014] FIG. 10 is a schematic illustration of a motor control arrangement for the generator inspection tool.

[0015] FIG. 11 is a schematic illustration of the movement of the camera mount of FIG. 7.

DETAILED DESCRIPTION

[0016] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in this description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0017] Various technologies that pertain to systems and methods will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0018] Also, it should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms “including,” “having,” and “comprising,” as well as derivatives thereof, mean inclusion without limitation. The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term “or” is inclusive, meaning and/or, unless the context clearly indicates otherwise. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Furthermore, while multiple embodiments or constructions may be described herein, any features, methods, steps, components, etc. described with regard to one embodiment are equally applicable to other embodiments absent a specific statement to the contrary.

[0019] Also, although the terms "first", "second", "third" and so forth may be used herein to refer to various elements, information, functions, or acts, these elements, information, functions, or acts should not be limited by these terms. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly, a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure.

[0020] In addition, the term "adjacent to" may mean that an element is relatively near to but not in contact with a further element, or that the element is in contact with the further portion, unless the context clearly indicates otherwise. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Terms “about” or “substantially” or like terms are intended to cover variations in a value that are within normal industry manufacturing tolerances for that dimension. If no industry standard is available, a variation of twenty percent would fall within the meaning of these terms unless otherwise stated.

[0021] FIG. 1 illustrates a generator 100 that includes a rotor 102 supported for rotation about a longitudinal or central axis 116. The rotor 102 is positioned within a stator 104 and cooperates with the stator 104 to define an annular air gap 112. The stator 104 is generally enclosed within a housing 114 that protects the stator 104 from the external environment.

[0022] The rotor 102 includes rotor windings 110 that are arranged around the rotor 102 and that are operable to generate a magnetic field when energized.

[0023] The stator 104 includes a plurality of laminations 106 that are stacked along the central axis 116 to define a stator core. An insulating layer 108 is typically positioned between each of the laminations 106 and acts to inhibit the flow of unwanted electrical currents between the laminations 106.

[0024] FIG. 2 is a longitudinal end view of the rotor 102 and the stator 104 in their operating positions better illustrating the air gap 112 therebetween. Each of the laminations 106 is shaped to define a plurality of radially extending teeth 202 with adjacent teeth 202 cooperating to define longitudinally extending slots 204 in which stator windings are positioned. [0025] The air gap 112 is annular in shape and provides a narrow space where in-situ inspection of parts of the rotor 102 and/Or stator 104 could be performed. However, typical generators are very long compared to the width of the air gap 112 such that full inspections of the length are very difficult.

[0026] FIG. 3 illustrates the rotor 102 and stator 104 positioned as in FIG. 2 to define the air gap 112. To facilitate the inspection of the rotor 102 and/or the stator 104 an inspection tool 400 is positioned within the air gap 112. As will be discussed in detail with regard to FIG. 4 through FIG. 11 the inspection tool 400 is arranged to fit within the air gap 112 and is operable to move in the longitudinal direction, substantially parallel to the central axis 116 to inspect the full length of the rotor 102 and/or the stator 104.

[0027] A portion of the inspection tool 400 is illustrated in FIG. 4. The inspection tool 400 includes a carriage 402, four drive assemblies 404, a camera assembly 600, and a sensor 410. The carriage 402 provides a structural body for the attachment and support of other components of the inspection tool 400. In some constructions, some or all of the carriage 402, and the other components discussed herein are additively manufactured to reduce the total number of parts and to allow for the formation of shapes or cavities that are otherwise not possible using conventional manufacturing techniques.

[0028] Each drive assembly 404 includes a motor 406, a belt 408, a permanent magnet 412, and a motor control 502 (shown in FIG. 5). In preferred constructions, each of the motors 406 is a DC motor that is driven by a separate motor control 502 that utilizes pulse width modulation (PWM) to control the speed and direction of operation of the motor 406. As is well known, the use of PWM during generator inspection can interfere with proper operation of the various sensors 410. However, by positioning the motor control 502 on the carriage 402 near the motor 406, this interference is greatly reduced.

[0029] Each motor 406 is arranged to drive a drive member in the form of a belt 408. In some constructions, the belt 408 is formed from a resilient material such as rubber to enhance the ability of the belt 408 to grip the rotor 102 or the stator 104. In addition, the lateral position of the belt 408 is adjustable to allow the belt 408 to engage teeth 202 of varying distance from one another. This adjustability allows for the use of the inspection tool 400 in generators 100 of varying size. [0030] In the illustrated construction, each drive assembly 404 also includes a permanent magnet 412 that engages the component along which the carriage is moving. For example, the permanent magnets 412 can engage the teeth 202 of the stator 104 to allow the belts 408 to frictionally engage the uppermost teeth 202 of the stator 104 despite their downward orientation. In other constructions, the permanent magnets are replaced or supplemented with electro-magnets. Electro-magnets provide the added advantage of being variable to allow for the adjustment of the magnetic force should such an adjustment be necessary. It should also be noted that while the illustrated construction includes four drive assemblies 404, other constructions may include fewer or more drive assemblies 404. In addition, not all the drive assemblies 404 need to be identical as some drive assemblies 404 could include additional features or omit features discussed herein.

[0031] The camera assembly 600 is positioned at the front or leading side of the carriage 402 to provide an unobstructed view of the rotor 102 or the stator 104 as it is being inspected. Of course, other locations are possible if desired. The camera assembly 600 includes a lateral camera motor 414, a vertical camera motor 416, a rotational camera motor 418, a block 424, a support member 422, and a camera mount 420. The lateral camera motor 414 includes a stepper motor or other type of motor that is operable to move and position the block 424 in a lateral direction (normal to the long axis of the carriage 402). The lateral camera motor 414 employs a belt drive to move and position the block 424 at any desired lateral position within the carriage 402. The vertical camera motor 416, the rotational camera motor 418, the support member 422, and the camera mount 420 are attached to the block 424 so that they each move laterally with the block 424.

[0032] The vertical camera motor 416 is coupled to the support member 422 and is arranged to rotate the support member 422 about a lateral axis that is fixed with respect to the carriage 402. The rotation of the support member 422 operates to move the camera mount 420 upward or downward with respect to the plane of the carriage 402. As with the lateral camera motor 414, the vertical camera motor 416 includes a stepper motor that allows for the precise positioning of the support member 422.

[0033] The rotational camera motor 418 is mounted to the block 424 and is operable to rotate the camera mount 420 about a lateral axis that is movable vertically with respect to the carriage 402. The rotation of the camera mount 420 about the lateral axis effectively moves the camera's field of view to a desired position along the longitudinal or central axis 116. As with the lateral camera motor 414 and the vertical camera motor 416, the rotational camera motor 418 includes a stepper motor that allows for the precise positioning of the camera mount 420.

[0034] The sensor 410 is mounted to the carriage 402 and can include any sensor 410 suitable for evaluating an operational property of the generator 100. In one construction, the sensor 410 includes a chattock coil that is used to measure the integrity of the insulating layer 108 between the adjacent laminations 106. Of course, other sensors 410 in place of or in conjunction with the chattock coil may be employed if desired. In addition, sensors 410 can be mounted in other locations not illustrated herein. Other sensors 410 could include but are not limited to laser measurement devices, stator wedge sensors (e.g., tightness), crack or NDE sensor for detecting rotor slot wedge cracks, and a mechanims for retrieving debris.

[0035] FIG. 5 illustrates the inspection tool 400 with an electronics cover removed to better illustrate the location of the motor controls 502 and an arrangement of carriage electronics 504. As discussed, each drive assembly 404 includes motor controls 502 that individually operate each motor 406. Thus, each motor 406 can be operated at a different speed and even in a different direction to turn or redirect the carriage 402 during motion. However, in straight line motion, each of the motors 406 is operated at the same speed and in the same direction.

[0036] The carriage electronics 504 include any electronics required to power and control the camera assembly 600, the sensors 410, and any other device such as a distance measuring device (e.g., laser) as well as any diagnostic electronics or signal conditioning electronics. The carriage electronics 504 are preferably surface mounted or embedded to reduce the need for additional wires.

[0037] In addition, the carriage electronics 504 may include on board diagnostics that will continuously monitor the operation of the inspection tool 400 and provide external feedback if a problem is detected. The motor current for each motor 406 can be monitored and if the current goes outside an expected parameter a message could be sent to a user. For example, if a measured current is too low, a message could be generated to inform the user that a motor amplifier has failed, or a wire has broken. If the measured current is too high, a message could be generated to inform the user that a motor 406 is starting to overheat or the mechanical friction in the system has increased. [0038] The carriage electronics 504 may also include signal conditioning circuitry that interfaces with the sensors 410 to provide a desired signal output and communication circuitry such as a serial interface or wireless interface for communication. In addition, the carriage electronics 504 could include a central processing unit (CPU), memory devices, data storage devices, communication devices, and the like that may be required for operation of the inspection tool 400.

[0039] FIG. 6 illustrates the camera assembly 600 in greater detail. As illustrated, the block 424 is supported and guided by a guide rail 606 that extends in the lateral direction. A lateral belt 604 is coupled to the lateral camera motor 414 which drives the lateral belt 604 to position the block 424 as desired.

[0040] The vertical camera motor 416 is directly connected to a first end of the support member 422 such that it can directly pivot the support member 422 which in turn moves the second end about the axis and vertically up or down. The rotational camera motor 418 is connected via a rotational belt 602 to the camera mount 420. Thus, the rotational camera motor 418 is able to position the camera mount 420 at any desired position around the vertically movable lateral axis of the camera mount 420 via the rotational belt 602 (See FIG. 11). In addition, the camera mount 420 is modular and therefore easy to remove, repair and replace as may be required. Of course, other connections or arrangements could be employed to adjust the position of the camera mount 420 or any camera or other sensor 410 mounted to the camera mount 420 (e.g., laser for measuring distance).

[0041] FIG. 7 better illustrates a front face of the camera mount 420. As illustrated, the camera mount 420 supports a camera 702 and one or more lights 704. The camera 702 is preferably a high-resolution color camera such as a CCD camera. Of course, other cameras including video or still cameras, infra-red cameras, black and white cameras, and the like could be employed in place of or in conjunction with the camera 702 illustrated in FIG. 7.

[0042] The lights 704 are preferably LED lights 704 that produce white or close to white light to fully illuminate the area being imaged. Of course, some inspections are enhanced by providing a different color of light and these LEDs could also be supported in the camera mount 420. The inspection tool 400 includes on-board electronics that allow the user to control the intensity (and color or EM range if available) of the lights 704 to assure that the area being imaged is properly illuminated. In some constructions, the lights 704 include LEDs that emit light in the visible range of the electromagnetic spectrum as well as LEDs that emit light in other ranges (e.g., infrared, ultraviolet, etc.).

[0043] In order to power the inspection tool 400 and to allow user control, a control cable 802 is connected to a carriage tail 808 of the inspection tool 400. The control cable 802 includes all the wires necessary to provide power to the inspection tool 400, provide control signals to the motors, controls, sensors, and other devices, and to receive output data from the various motors, sensors, and other components. It is important to note that the use of embedded electronics reduces the number of wires needed in the control cable 802. The reduction in wires also reduces the load on the motors 406 as they are required to pull the control cable 802 through the generator 100 during an inspection.

[0044] A cable clamp 804 is used to clamp the control cable 802 to the carriage tail 808 in a manner that assures that the individual wires within the control cable 802 are not overly stressed as the control cable 802 is dragged by the movement of the inspection tool 400. A cable connector 806 is provided on the interior of the carriage tail 808 to attach the wires to the carriage electronics 504.

[0045] The cable clamp 804 is better illustrated in FIG. 9. The cable clamp 804 includes an aperture sized to receive the control cable 802 and to squeeze the control cable 802 to inhibit unwanted movement. The cable clamp 804 also includes one or more cable clamp tabs 904 that, in the illustrated construction are tapered. Corresponding tapered cable clamp grooves 902 are formed as part of the carriage tail 808. The cable clamp 804 is positioned such that the cable clamp tabs 904 engage the cable clamp grooves 902 to inhibit unwanted movement of the control cable 802. As tension is applied to the control cable 802 the cable clamp 804 is more tightly engaged in the carriage tail 808.

[0046] As illustrated in FIG. 10, the inspection tool 400 includes on-board motor diagnostics to assure that the individual motors 406 are operating properly. Specifically, as illustrated in FIG. 10, a current sensor 1002 is positioned to monitor the current flowing to each motor 406. The output of the current sensor is provided to the onboard inspection tool CPU and can be analyzed to assure proper motor operation. The results of the analysis and/or the measured current data can be transmitted through the control cable 802 (i.e., via a serial interface) to the user for review and action as may be required. Each of the motors 406 includes its own current sensor 1002 such that each motor 406 is monitored individually.

[0047] In operation, the user places the inspection tool 400 in the air gap 112 between the rotor 102 and the stator 104. The permanent magnets 412 magnetically engage the teeth 202 of the stator 104 to hold the inspection tool 400 in positions where gravity does not hold the inspection tool 400 in place. The motors 406 can then be operated to move the inspection tool 400 along the length of the stator 104. As the inspection tool 400 moves, it drags the control cable 802 and images any desired location. A laser can be employed to measure the position of the inspection tool 400 or the position being imaged with respect to the stator 104 to assure that the position of any image can be found at a later date or re-inspected.

[0048] Placing the PWM motor drives on the carriage 402 removes undesirable noise issues that could interfere with the proper operation of the chattock coil or the video signals.

[0049] In addition, the use of 3D printed parts allows for more complicated designs that are not possible with traditional machining methods. This reduces the price of the parts and the number of components needed. Reducing the number of components has the benefit of making the tool more reliable and lowers the chance of losing a part in the generator 100 during operation.

[0050] The laser is capable of taking measurements inside the stator core including measurements of the axial distance down the stator slot. The laser may also be capable of measuring the size of an object. Specifically, and as illustrated in Fig. 11 the angles a and 0 are known based on the positions of the stepper motors 416, 418 and the laser can measure the distance 24 from camera to the point of interest. The distance C is easily calculated using the equation C = B [Sin (0) / Sin (180 - a - 0)].

[0051] Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form.

[0052] None of the description in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be included in the claim scope: the scope of patented subject matter is defined only by the allowed claims. Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.

Claims

CLAIMS What is claimed is:

1. An inspection tool for inspecting a stator of a generator with a rotor positioned within the stator, the inspection tool comprising: a carriage sized to fit within a gap between the rotor and the stator; a drive assembly coupled to the carriage, the drive assembly including a drive motor operable to move the carriage along the stator in an axial direction; a motor control operable using pulse width modulation to operate the drive motor; a sensor operable to sense a feature of the stator; and a distance measuring device coupled to the carriage and operable to measure the position of the carriage with respect to the stator.

2. The inspection tool of claim 1, wherein the drive motor is a first drive motor, and wherein the drive assembly further comprises a second drive motor, a third drive motor, and a fourth drive motor each coupled to the carriage.

3. The inspection tool of claim 2, wherein the motor control is a first motor control, the inspection tool further comprising a second motor control, a third motor control, and a fourth motor control, the second motor control using pulse width modulation to operate the second drive motor, the third motor control using pulse width modulation to operate the third drive motor, and the fourth motor control using pulse width modulation to operate the fourth drive motor, each of the first motor control, the second motor control, the third motor control, and the fourth motor control fixedly connected to the carriage and operable independent of one another.

4. The inspection tool of claim 2, further comprising a first current sensor operable to measure the current used by the first motor, a second current sensor operable to measure the current used by the second motor, a third current sensor operable to measure the current used by the third motor, and a fourth current sensor operable to measure the current used by the fourth motor, the first current sensor, the second current sensor, the third current sensor, and the fourth current sensor fixedly connected to the carriage.

5. The inspection tool of claim 1, wherein the sensor includes a chattock coil operable to measure s resistance between a first stator lamination and a second stator lamination.

6. The inspection tool of claim 1, further comprising a camera assembly movable coupled to the carriage and including a camera operable to capture an image.

7. The inspection tool of claim 6, further comprising a first stepper motor operable to position the camera along a first axis, a second stepper motor operable to position the camera along an arc centered on the first axis, and a third stepper motor operable to rotate the camera around a second axis that is parallel to and offset from the first axis.

8. The inspection tool of claim 6, further comprising a light emitting diode positioned within the camera assembly.

9. An inspection tool for inspecting a stator of a generator with a rotor positioned within the stator, the inspection tool comprising: a carriage sized to fit within a gap between the rotor and the stator; a first drive member coupled to the carriage and operable to move the carriage in the axial direction; a first drive motor coupled to the drive member; a first motor control operable using pulse width modulation to drive the first drive motor; a chattock coil coupled to the carriage, the chattock coil including a signal conditioner mounted to the carriage; a camera coupled to the carriage and movable to image a desired location; a laser coupled to the carriage and operable to measure the position of the carriage with respect to the stator; a control cable; and a cable clamp arranged to couple the control cable to the carriage.

10. The inspection tool of claim 9, further comprising a second drive motor, a third drive motor, and a fourth drive motor each coupled to the carriage.

11. The inspection tool of claim 10, further comprising a second motor control, a third motor control, and a fourth motor control, the second motor control using pulse width modulation to operate the second drive motor, the third motor control using pulse width modulation to operate the third drive motor, and the fourth motor control using pulse width modulation to operate the fourth drive motor, each of the first motor control, the second motor control, the third motor control, and the fourth motor control fixedly connected to the carriage and operable independent of one another.

12. The inspection tool of claim 10, further comprising a first current sensor operable to measure the current used by the first motor, a second current sensor operable to measure the current used by the second motor, a third current sensor operable to measure the current used by the third motor, and a fourth current sensor operable to measure the current used by the fourth motor, the first current sensor, the second current sensor, the third current sensor, and the fourth current sensor fixedly connected to the carriage.

13. The inspection tool of claim 9, further comprising a first stepper motor operable to position the camera along a first axis, a second stepper motor operable to position the camera along an arc centered on the first axis, and a third stepper motor operable to rotate the camera around a second axis that is parallel to and offset from the first axis.

14. The inspection tool of claim 9, further comprising a light emitting diode coupled to the carriage and positioned to illuminate an area for the camera.

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