Abstract
A method for performing a plurality of measurements in the air gap between a stator and a rotor of a generator for a wind turbine is provided The method steps include: mounting distance measuring sensors on a surface of the stator and/or the rotor, the surface facing the air gap, each distance measuring sensor distanced from the other distance measuring sensor(s) along rotational axis, rotating the rotor about the rotational axis, while rotating the rotor, measuring distances between the distance measuring sensors and respective facing points across the air gap, deriving from the distances one or more value(s) of one or more parameter(s) associated with the air gap and/or the stator and/or rotor, wherein a portion of distance measuring sensors are fixed to a longitudinal support, the longitudinal support being fixed on a surface of the stator and/or the rotor, the surface facing the air gap, during the step of mounting.
Claims
1. A method for performing a plurality of measurements in the air gap between a stator and a rotor of a generator for a wind turbine, the rotor being rotatable with respect to the stator about a rotational axis, the method including: mounting a plurality of distance measuring sensors on at least one surface of the stator and/or the rotor, the surface facing the air gap, each distance measuring sensor being distanced from the other distance measuring sensor(s) along the rotational axis; rotating the rotor about the rotational axis; while rotating the rotor, measuring a plurality of distances between each of the distance measuring sensors and respective facing points across the air gap; deriving from the plurality of distances one or more value(s) of one or more parameter(s) associated with the air gap and/or the stator and/or rotor, and wherein at least a portion of plurality of distance measuring sensors are fixed to a longitudinal support, the longitudinal support being fixed on a surface of the stator and/or the rotor, the surface facing the air gap, during the step of mounting.
2. The method according to claim 1, wherein the steps of mounting, rotating and measuring are first performed with the plurality of distance measuring sensors mounted on one of the stator and the rotor and then the steps of mounting, rotating and measuring are again performed with the plurality of distance measuring sensors mounted on the other of the rotor and the stator.
3. The method according to claim 1, wherein in the step of mounting a first plurality of distance measuring sensors are mounted on a first surface of the stator and a second plurality of distance measuring sensors are mounted on a second surface of the rotor, the first and second surfaces facing the air gap.
4. The method according to claim 1, wherein the longitudinal support mounted with an angle of inclination () comprised between 0 and 10 degrees with respect to the rotational axis.
5. The method according to claim 1, wherein the one or more parameter(s) associated with the air gap is any of: a thickness of the air gap, and/or a rotor roundness, and/or a stator roundness, and/or a rotor concentricity, and/or a stator concentricity, and/or distance of the rotor center from a reference position, and/or distance of the stator center from a reference position.
6. The method according to claim 1, wherein the longitudinal support is fixed to the stator or the rotor by at least one thread.
7. The method according to claim 6, wherein each thread grasps the longitudinal support and extends through a respective air duct of the stator, the thread being tightened in such a way that the longitudinal support is pushed against the external side of the stator.
8. The method according to claim 1, wherein the longitudinal support is fixed to the rotor by applying un under-pressure between the longitudinal support and a surface of the stator or the rotor facing the air gap, the under-pressure pushing the longitudinal support towards the surface of the stator or the rotor facing the air gap.
9. A measurement device for performing a plurality of measurements in the air gap between a stator and a rotor of a generator for a wind turbine, the measurement device including: a plurality of distance measuring sensors mounted on a longitudinal support, a controller connected to the plurality of distance measuring sensors configured for deriving from a plurality of distances measured by the sensors one or more value(s) of one or more parameter(s) associated with the air gap and/or the stator and/or rotor, when the steps of the method according to claim 1 are being performed.
10. The measurement device according to claim 9, wherein the plurality of distance measuring sensors are capacitive sensors.
11. The measurement device according to claim 9, wherein the measurement device comprises one or more threads for fixing the longitudinal support the stator or the rotor.
12. The measurement device according to claim 11, further comprising a tightener for tightening the thread.
13. The measurement device according to claim 9, wherein the longitudinal support comprises a channel having an opening to be attached to a surface of the stators or the rotor facing the air gap, the measurement device comprising an under-pressure generator to be connected to the channel for evacuating air is activated, air can be evacuated from the opening.
14. The measurement device according to claim 13, wherein the opening is surrounded by a sealing.
Description
BRIEF DESCRIPTION
[0041] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:
[0042] FIG. 1 shows a schematic section of a wind turbine including an electric generator;
[0043] FIG. 2 shows an exploded view of the stator and rotor of the electric generator of FIG. 1.
[0044] FIG. 3 shows a block diagram illustrating a first embodiment of a measurement method according to the present invention for performing a plurality of measurements in the air gap of the electric generator of FIGS. 1 and 2;
[0045] FIG. 4 shows a block diagram illustrating a second embodiment of a measurement method according to the present invention for performing a plurality of measurements in the air gap of the electric generator of FIGS. 1 and 2;
[0046] FIG. 5 shows a partial view of an assembly of the stator of the electric generator of FIGS. 1 and 2 and a measurement device according to embodiments of the present invention;
[0047] FIG. 6 shows a partial view of an assembly of the electric generator of FIGS. 1 and 2 and a measurement device according to embodiments of the present invention;
[0048] FIG. 7 shows a step of the measurement method of embodiments of the present invention illustrating the fixing of the measurement device to the rotor of the electric generator;
[0049] FIG. 8 shows a more detailed view of the step of the measurement method of FIG. 7; and
[0050] FIG. 9 shows a partial front view of an assembly of the stator of the electric generator of FIGS. 1 and 2, a measurement device according to embodiments of the present invention and means for fixing the measurement device to the stator.
[0051] FIG. 10 shows a rear partial view of the assembly of FIG. 9.
[0052] FIG. 11 shows a partial front view of an assembly of the rotor of the electric generator of FIGS. 1 and 2, a measurement device according to embodiments of the present invention and means for fixing the measurement device to the rotor.
[0053] FIG. 12 shows more in detail the assembly of the rotor of the electric generator of FIGS. 1 and 2 and of the measurement device according to embodiments of the present invention.
[0054] FIG. 13 shows means for fixing the measurement device according to embodiments of the present invention to the rotor.
DETAILED DESCRIPTION
[0055] FIG. 1 shows a wind turbine 1 according to embodiments of the invention. The wind turbine 1 comprises a tower 2, which is mounted on a non-depicted foundation. A nacelle 3 is arranged on top of the tower 2. The wind turbine 1 further comprises at least a wind rotor 5 having a hub and at least one blade 4 (in the embodiment of FIG. 1, the wind rotor comprises three blades 4, of which only two blades 4 are visible). The wind rotor 5 is rotatable around a rotational longitudinal axis Y. The blades 4 extend substantially radially with respect to the longitudinal rotational axis Y. In general, when not differently specified, the terms axial, radial and circumferential in the following are made with reference to the longitudinal rotational axis Y. The wind turbine 1 comprises at least one electric generator 11, including a stator 20 and a rotor 30. The rotor 30 is rotatable with respect to the stator 20 about the longitudinal rotational axis Y. The wind rotor 5 is coupled with the rotor 30, in order to rotate about the rotational longitudinal axis Y. The electric generator 11 comprise an airgap 15 radially interposed between the stator 20 and the rotor 30, the airgap 15 extending circumferentially about the rotational axis Y. In the embodiment of the attached figures the rotor 30 is radially external to the stator 20. According to other embodiments (not show), the rotor may be radially internal to the stator.
[0056] FIG. 2 shows an exploded view of the electrical generator 11 with the rotor 30 and the stator 20. The stator 20 comprises a cylindrical inner core to which six segments 45 are attached. Each segment 45 has a circumferential angular extension of 60. According to other embodiments of the present invention, the stator 20 comprises a plurality of segments having a number of segments different from six. According to another possible embodiment of the present invention, the stator 20 is not segmented, i.e., the stator includes one single segment covering the entire angular extension of 360. The rotor 30 has a conventional structure with a plurality of circumferentially distributed rotor permanent magnets 31. The magnets 31 are distributed on an inner side of the rotor 30 according to axial columns. Each column of magnets comprises a plurality of magnets 31 (two magnets 31 in the embodiment of FIG. 2) aligned along the rotational axis Y.
[0057] FIGS. 3 and 4 show two respective block diagrams of a method 100 for performing a plurality of measurements in the air gap 15. Such method may be performed during the manufacturing of the electric generator, for example as quality check.
[0058] A method 100 for performing a plurality of measurements in the air gap 15 includes the following steps: [0059] a first step 101 of mounting a plurality of distance measuring sensors 210 on at least one respective surface of the stator 20 and/or the rotor 30. The surface(s) face the air gap 15, each distance measuring sensor 210 being distanced from the other distance measuring sensor(s) 210 along the rotational axis Y, [0060] a second step 102 of rotating the rotor 30 about the rotational axis Y, [0061] a third step 103 of, while rotating the rotor 30, measuring a plurality of distances between each of the distance measuring sensors 210 and respective facing points across the air gap 15, [0062] a fourth step 104 of data analysis for deriving from the plurality of measured distances one or more value(s) of one or more parameter(s) associated with the air gap 15 and/or the stator and/or rotor 30.
[0063] Such parameter(s) associated with the air gap 15 may be one or more of: [0064] a thickness of the air gap, [0065] a rotor roundness, [0066] a stator roundness, [0067] a rotor concentricity, [0068] a stator concentricity, [0069] distance of the rotor center from a reference position, [0070] distance of the stator center from a reference position.
[0071] FIG. 3 shows a first embodiment of a block diagram of a method 100. In a first execution of the first step 101, the method 100 comprises mounting a plurality of distance measuring sensors 210 on a surface of the stator 20 facing the air gap 15 (FIGS. 5 and 6). For example, the sensors 210 may be attached to an external surface of a stator segment 45. The plurality of distance measuring sensors 110 may be alternatively mounted on a surface of the rotor 30 facing the air gap 15. The sensors 210 are fixed to the stator 20 or rotor 30 in such a way that each distance measuring sensor 210 is distanced from the other distance measuring sensors 210 along the rotational axis Y. After the first step 101 the rotor 30 and the stator 20 are paired and a break disc 46 (shown in FIGS. 6 and 7) is attached to the generator 11. In a first execution of the second step 102 the method 100 comprises rotating the rotor 30 about the rotational axis Y. A complete rotation of 360 degrees or more may be executed. The rotation of the rotor 30 is initiated and stopped by an external device. In a first execution of the third step 103 of the method 100 comprises, while rotating the rotor 30, measuring a first plurality of distances between each of the distance measuring sensors 210, which has been mounted during the first step 101 of the method, and respective facing points across the air gap 15. After the third step 103 the sensors 210, which have been mounted during the first execution of the first step 101, are removed. The first step 101 of the method 100 is then repeated mounting the same or another plurality of distance measuring sensors 210 on a surface of the rotor 30 facing the air gap 15 (FIG. 7). For example, the sensors 210 may be attached to the magnets 31. The plurality of distance measuring sensors 110 may be alternatively mounted on a surface of the stator 20 facing the air gap 15, if in the previous execution of the first step 101 distance measuring sensors 210 were mounted on the rotor 30. A second execution of the second step 102 and third step 103 is also performed for measuring a second plurality of distances by the distance measuring sensors 210. After the third step 103 the sensors 210, which have been mounted during the second execution of the first step 101, are removed and the final fourth step 104 is performed.
[0072] FIG. 4 shows a second embodiment of a block diagram of a method 100. In the first step 101, the method 100 comprises mounting a first plurality of distance measuring sensors 210 on a surface of the stator 20 facing the air gap 15 (FIG. 5). For example, the sensors 210 may be attached to an external surface of a stator segment 45. The rotor 30 and the stator 20 are then paired. In the first step 101, the method 100 further comprises mounting a second plurality of distance measuring sensors 110 on a surface of the rotor 30 facing the air gap 15. For example, the sensors 210 may be attached to the magnets 31. The sensors 210 are fixed to the stator 20 and rotor 30 in such a way that each distance measuring sensor 210 is distanced from the other distance measuring sensors 210 along the rotational axis Y. After that the break disc 46 is attached to the generator 11. The second step 102 of the method 100 is executed by rotating the rotor 30 about the rotational axis Y. A complete rotation of 360 degrees or more may be executed. The rotation of the rotor 30 is initiated and stopped by an external device. The third step 103 of the method 100 is then executed, while rotating the rotor 30, for measuring a plurality of distances between each of the distance measuring sensors 210, which has been mounted during the first step 101 of the method, and respective facing points across the air gap 15. The plurality of distances measured during the third step 103 includes the measurement performed with the first plurality of sensors 210 and the second plurality of sensors 210 installed during the first step 101. After the third step 103 the sensors 210 are removed and the final fourth step 104 is performed.
[0073] FIG. 5 shows the coupling between a plurality of sensors 210 and a segment 45 of the stator 20, performed during the first step 101 of the method 100. The distance measuring sensors 210 are comprised in a measurement device 200, which also includes a longitudinal support 220, for example a stick, on which the sensors 210 are fixed and a controller 230 connected to the plurality of distance measuring sensors 210, for example by a cable 240, and configured for performing the steps of the method 100. The measurement device 200 of FIG. 5 includes six distance measuring sensors 210. According to other embodiments (not shown), the measurement device 200 of FIG. 5 may include two or more distance measuring sensors 210. The measuring sensors 210 may be capacitive sensors. For example, the measuring sensors 210 may be capacitive film sensors or capacitive flat sensors. According to other embodiments (not shown), the longitudinal support 220 may include one or more cable ties, screws, rubber bands, a knee-lever system or similar. The longitudinal support 220 may be tightened on the outer surface of the segment 45 with any tightening means.
[0074] FIG. 6 shows the pairing between the stator 20 and the rotor 30 and the mounting of the break disc 46, performed after the first execution of the step 101 in the first embodiment (FIG. 3) of the method 100.
[0075] FIG. 7 shows the coupling between a plurality of sensors 210 and the rotor 30, performed during the second execution of the first step 101 in the first embodiment (FIG. 3) of the method 100. The distance measuring sensors 210 are comprised in the same measurement device 200 used during the first execution of the step 101 (FIG. 5) or in another measurement device 200. In order to facilitate the coupling between the measuring sensors 210 and the magnets 31, the longitudinal support 220 comprises a metallic material that has low magnetic properties. The length of the longitudinal support 220 may be in the range of some. A correct positioning may therefore require a guide for the longitudinal support 220.
[0076] FIG. 8 shows a guide 250 temporarily attached to the break disc 46 for introducing the longitudinal support 220 and the plurality of sensors 210 to be attached to the rotor 30 through an inspection hole 47 of the break disc 46. The longitudinal support 220 is inserted through the guide 250 and the inspection hole 47 of the break disc 46 and mounted on the rotor 30 with an angle of inclination , which may be comprised between 0 and 10 degrees with respect to the rotational axis Y. the angle of inclination a depends on the geometrical constraints of the assembly including the stator 20 and the rotor 30.
[0077] According to other embodiments (not shown), the break disc 46 is not mounted when the longitudinal support 220 is to be coupled to the rotor 30, for example during the first step 101 in the second embodiment (FIG. 4) of the method 100. In such a case another component of the electric generator 11 may be used for mounting the guide 250.
[0078] FIGS. 9 and 10 show more in detail, with respect to FIG. 5, the coupling between a plurality of sensors 210 fixed on the longitudinal support 220 and a segment 45 of the stator 20. The segment comprises a plurality of segment axial portions 48 which are arrayed along the longitudinal or rotational axis Y. The segment axial portions 48 are separated from each other by air ducts 55 for letting a cooling fluid flow in the air duct 55. Each segment axial portion 48 may be formed of a plurality of laminations stacked along the longitudinal axis Y to form the segment 45. At each air duct 55 the lamination stack is discontinued, and a plurality of spacers 56 are provided in the air duct 55 between the two respective and axially adjacent segment axial portions 48. The measurement device 200 comprises one or more threads 225 (six threads 225 in the embodiment shown in FIG. 9), each thread 225 extending through a respective air duct 55. The thread 225 grasps the longitudinal support 220 and is tightened in such a way that the longitudinal support 220 is pushed against the external side of the stator segment 45 (FIG. 9). On the opposite internal side of stator segment 45 (FIG. 10) a respective thread tightener 226 is provided to tighten the thread 225. The thread 225 may be made on nylon or other similar material. According to other embodiments of the invention, threads 225 may be used to fix the longitudinal support 220 to the rotor 30.
[0079] FIGS. 11 to 13 show the coupling between a plurality of sensors 210 fixed on the longitudinal support 220 and the rotor 30. An under-pressure is applied to the longitudinal support 220 to fix the longitudinal support 220 on a respective magnet 31. According to other embodiments of the invention, an under-pressure may be applied to the longitudinal support 220 to fix the longitudinal support 220 on a respective surface of the rotor facing the air gap 15. The under-pressure is applied by an under-pressure device 227 having an under-pressure generator 228 connected to an air cable 229 (FIG. 11). The longitudinal support 220 to be coupled to be attached to the rotor 30 may comprise to such purpose a channel to be coupled to under-pressure generator 228 via the air cable 229, the channel 221 having an opening 231 surrounded by a sealing 232 to be attached to a respective magnet 31. The opening 231 is provided on the surface of the longitudinal support 220 which is subject to contact the magnet 31 in operation (therefore the opening 231 is not visible in FIG. 12, but it is shown in FIG. 13). When the under-pressure generator 228 is activated, air can be evacuated from the opening 231 towards the air cable 229, thus generating the under-pressure which pushes the opening 231 of the longitudinal support 220 towards the respective magnet 31. According to other embodiments of the invention, an under-pressure may be applied to the longitudinal support 220 to fix the longitudinal support 220 to the stator 20.
[0080] Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
[0081] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.
